Science.gov

Sample records for cw resonance ionization

  1. Attogram measurement of rare isotopes by CW resonance ionization mass spectrometry

    SciTech Connect

    Bushaw, B.A.

    1992-05-01

    Three-color double-resonance ionization mass spectrometry, using two single-frequency cw dye lasers and a cw carbon dioxide laser, has been applied to the detection of attogram quantities of rare radionuclides. {sup 210}Pb has been measured in human hair and brain tissue samples to assess indoor radon exposure. Measurements on {sup 90}Sr have shown overall isotopic selectivity of greater than 10{sup 9} despite unfavorable isotope shifts relative to the major stable isotope, {sup 88}Sr.

  2. Resonance Ionization, Mass Spectrometry.

    ERIC Educational Resources Information Center

    Young, J. P.; And Others

    1989-01-01

    Discussed is an analytical technique that uses photons from lasers to resonantly excite an electron from some initial state of a gaseous atom through various excited states of the atom or molecule. Described are the apparatus, some analytical applications, and the precision and accuracy of the technique. Lists 26 references. (CW)

  3. Resonance ionization for analytical spectroscopy

    DOEpatents

    Hurst, George S.; Payne, Marvin G.; Wagner, Edward B.

    1976-01-01

    This invention relates to a method for the sensitive and selective analysis of an atomic or molecular component of a gas. According to this method, the desired neutral component is ionized by one or more resonance photon absorptions, and the resultant ions are measured in a sensitive counter. Numerous energy pathways are described for accomplishing the ionization including the use of one or two tunable pulsed dye lasers.

  4. Ionization Cooling using Parametric Resonances

    SciTech Connect

    Johnson, Rolland P.

    2008-06-07

    Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been

  5. Astatine and Yttrium Resonant Ionization Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Teigelhoefer, Andrea

    Providing intense, contamination-free beams of rare isotopes to experiments is a challenging task. At isotope separator on-line facilities such as ISAC at TRIUMF, the choice of production target and ion source are key to the successful beam delivery. Due to their element-selectivity, high efficiency and versatility, resonant ionization laser ion sources (RILIS) gain increasingly in importance. The spectroscopic data available are typically incomplete in the region of excited- and autoionizing atomic states. In order to find the most efficient ionization scheme for a particular element, further spectroscopy is often required. The development of efficient laser resonant ionization schemes for yttrium and astatine is presented in this thesis. For yttrium, two ionization schemes with comparable relative intensities were found. Since for astatine, only two transitions were known, the focus was to provide data on atomic energy levels using resonance ionization spectroscopy. Altogether 41 previously unknown astatine energy levels were found.

  6. CW YVO4:Er Laser with Resonant Pumping

    NASA Astrophysics Data System (ADS)

    Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Matrosov, V. N.; Tolstik, N. A.; Kuleshov, N. V.

    2015-05-01

    The lasing characteristics of a YVO4:Er laser with resonant pumping in the 1.5-1.6 μm range are studied. Lasing is obtained at λ = 1603 nm with a differential efficiency of up to 61%. YVO4:Er crystals are found to offer promise for use in efficient resonantly (in-band) pumped lasers.

  7. Conceptual basis of resonance ionization spectroscopy

    SciTech Connect

    Payne, M.G.

    1984-04-01

    Resonance Ionization Spectroscopy (RIS) can b defined as a state-selective detection process in which tunable lasers are used to promote transitions from the selected state of the atoms or molecules in question to higher states, one of which will be ionized by the absorption of another photon. At least one resonance step is used in the stepwise ionization process, and it has been shown that the ionization probability of the spectroscopically selected species can nearly always be made close to unity. Since measurements of the number of photoelectrons or ions can be made very precisely and even one electron (or under vacuum conditions, one ion) can be detected, the technique can be used to make quantitative measurements of very small populations of the state-selected species. Counting of individual atoms has special meaning for detection of rare events. The ability to make saturated RIS measurements opens up a wide variety of applications to both basic and applied research. We view RIS as a specific type of multi-photon ionization in which the goal is to make quantitative measurements of quantum-selected populations in atomic or molecular systems. 16 references.

  8. Ionization Cooling Using a Parametric Resonance

    SciTech Connect

    Y.S. Derbenev; R.P. Johnson

    2005-05-16

    Muon collider luminosity depends on the number of muons in the storage ring and on the transverse size of the beams in collision. Ionization cooling as it is presently envisioned will not cool the beam sizes sufficiently well to provide adequate luminosity without large muon intensities. A new idea to combine ionization cooling with parametric resonances has been developed that will lead to beams with much smaller sizes so that high luminosity in a muon collider can be achieved with fewer muons. In the linear channel described here, a half integer resonance is induced such that the normal elliptical motion of particles in x-x' phase space becomes hyperbolic, with particles moving to smaller x and larger x' as they pass down the channel. Thin absorbers placed at the focal points of the channel then cool the angular divergence of the beam by the usual ionization cooling mechanism where each absorber is followed by RF cavities. We discuss the theory of Parametric-resonance Ionization Cooling, including the sensitivity to aberrations and the need to start with a beam that has already been cooled adequately.

  9. Historical survey of resonance ionization spectroscopy

    SciTech Connect

    Hurst, G.S.

    1984-04-01

    We have recently celebrated the 10th birthday of Resonance Ionization Spectroscopy (RIS), and this seems an appropriate time to review the history of its development. Basically, RIS is a photophysics process in which tunable light sources are used to remove a valence electron from an atom of selected atomic number, Z. If appropriate lasers are used as the light source, one electron can be removed from each atom of the selected Z in the laser pulse. This implies that RIS can be a very efficient, as well as selective, ionization process. In what we normally call RIS, laser schemes are employed which preserve both of these features. In contrast, multiphoton ionization (MPI) is more general, although not necessarily Z selective or very efficient because resonances are often not used. Early research completed in the USSR and described as selective two-step photoionization, employed resonances to ionize the rubidium atom and served to guide work on laser isotope separation. 29 references, 8 figures.

  10. Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

    PubMed

    Atutov, S N; Baldini, W; Biancalana, V; Calabrese, R; Guidi, V; Mai, B; Mariotti, E; Mazzocca, G; Moi, L; Pod'yachev, S P; Tomassetti, L

    2001-11-19

    Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process. PMID:11736344

  11. Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

    PubMed

    Atutov, S N; Baldini, W; Biancalana, V; Calabrese, R; Guidi, V; Mai, B; Mariotti, E; Mazzocca, G; Moi, L; Pod'yachev, S P; Tomassetti, L

    2001-11-19

    Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process.

  12. Resonance ionization mass spectrometry for isotopic abundance measurements

    NASA Technical Reports Server (NTRS)

    Miller, C. M.

    1986-01-01

    Resonance ionization mass spectrometry (RIMS) is a relatively new laser-based technique for the determination of isotopic abundances. The resonance ionization process depends upon the stepwise absorption of photons from the laser, promoting atoms of the element of interest through progressively higher electronic states until an ion is formed. Sensitivity arises from the efficiency of the resonant absorption process when coupled with the power available from commercial laser sources. Selectivity derives naturally from the distinct electronic structure of different elements. This isobaric discrimination has provided the major impetus for development of the technique. Resonance ionization mass spectrometry was used for analysis of the isotopic abundances of the rare earth lutetium. Isobaric interferences from ytterbium severely effect the ability to measure small amounts of the neutron-deficient Lu isotopes by conventional mass spectrometric techniques. Resonance ionization for lutetium is performed using a continuous-wave laser operating at 452 nm, through a sequential two-photon process, with one photon exciting the intermediate resonance and the second photon causing ionization. Ion yields for microgram-sized quantities of lutetium lie between 10(6) and 10(7) ions per second, at overall ionization efficiencies approaching 10(-4). Discrimination factors against ytterbium greater than 10(6) have been measured. Resonance ionization for technetium is also being explored, again in response to an isobaric interference, molybdenum. Because of the relatively high ionization potential for Tc, three-photon, two-color RIMS processes are being developed.

  13. Epicyclic helical channels for parametric resonance ionization cooling

    SciTech Connect

    Johson, Rolland Paul; Derbenev, Yaroslav

    2015-08-23

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

  14. CW and pulsed electrically detected magnetic resonance spectroscopy at 263GHz/12T on operating amorphous silicon solar cells.

    PubMed

    Akhtar, W; Schnegg, A; Veber, S; Meier, C; Fehr, M; Lips, K

    2015-08-01

    Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263GHz and resonance fields between 0 and 12T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5K and 90K was studied by in operando 263GHz CW and pEDMR alongside complementary X-band CW EDMR. Benefiting from the superior resolution at 263GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5K EDMR spectra were found to be dominated by conduction and valence band tail states involved in spin dependent hopping, with additional contributions from triplet exciton states. 90K EDMR spectra could be assigned to spin pair recombination involving conduction band tail states and dangling bonds as the dominating spin dependent transport process, with additional contributions from valence band tail and triplet exciton states.

  15. CW and pulsed electrically detected magnetic resonance spectroscopy at 263GHz/12T on operating amorphous silicon solar cells.

    PubMed

    Akhtar, W; Schnegg, A; Veber, S; Meier, C; Fehr, M; Lips, K

    2015-08-01

    Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263GHz and resonance fields between 0 and 12T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5K and 90K was studied by in operando 263GHz CW and pEDMR alongside complementary X-band CW EDMR. Benefiting from the superior resolution at 263GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5K EDMR spectra were found to be dominated by conduction and valence band tail states involved in spin dependent hopping, with additional contributions from triplet exciton states. 90K EDMR spectra could be assigned to spin pair recombination involving conduction band tail states and dangling bonds as the dominating spin dependent transport process, with additional contributions from valence band tail and triplet exciton states. PMID:26112328

  16. Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2008-07-15

    Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

  17. Resonant Ionization Laser Ion Source for Radioactive Ion Beams

    SciTech Connect

    Liu, Yuan; Beene, James R; Havener, Charles C; Vane, C Randy; Gottwald, T.; Wendt, K.; Mattolat, C.; Lassen, J.

    2009-01-01

    A resonant ionization laser ion source based on all-solid-state, tunable Ti:Sapphire lasers is being developed for the production of pure radioactive ion beams. It consists of a hot-cavity ion source and three pulsed Ti:Sapphire lasers operating at a 10 kHz pulse repetition rate. Spectroscopic studies are being conducted to develop ionization schemes that lead to ionizing an excited atom through an auto-ionization or a Rydberg state for numerous elements of interest. Three-photon resonant ionization of 12 elements has been recently demonstrated. The overall efficiency of the laser ion source measured for some of these elements ranges from 1 to 40%. The results indicate that Ti:Sapphire lasers could be well suited for laser ion source applications. The time structures of the ions produced by the pulsed lasers are investigated. The information may help to improve the laser ion source performance.

  18. Prediction and identification of multiple-photon resonant ionization processes

    SciTech Connect

    Smith, D.H.; McKown, H.S.; Young, J.P.; Shaw, R.W.; Donohue, D.L.

    1988-08-01

    Many single-color, multiple-photon transitions leading to ionization are observed for lanthanide and actinide elements in experiments using resonance ionization mass spectrometry (RIMS). It is desirable both to identify the energy levels involved in observed transitions and to be able to predict in advance their location. A computer code, ETRANS, has been written to perform these functions. Examples of both types of operation are given.

  19. Time-resolved view on charge-resonance-enhanced ionization

    SciTech Connect

    Takemoto, Norio; Becker, Andreas

    2011-08-15

    We theoretically investigate the electronic dynamics in the hydrogen molecular ion at fixed intermediate internuclear distances in two-dimensional space for the electron in a linearly polarized laser field. Our results of numerical simulations confirm the predictions of multiple bursts of ionization within a half cycle of the laser field oscillation as recently reported for one-dimensional models. Based on the analysis of the Floquet states for a two-state model of the molecular ion, we discuss the relation of the multiple ionization bursts to the so-called charge-resonance-enhanced ionization phenomenon and the momentum gates.

  20. Resonance ionization detection of combustion radicals

    SciTech Connect

    Cool, T.A.

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  1. High resolution resonance ionization imaging detector and method

    DOEpatents

    Winefordner, James D.; Matveev, Oleg I.; Smith, Benjamin W.

    1999-01-01

    A resonance ionization imaging device (RIID) and method for imaging objects using the RIID are provided, the RIID system including a RIID cell containing an ionizable vapor including monoisotopic atoms or molecules, the cell being positioned to intercept scattered radiation of a resonance wavelength .lambda..sub.1 from the object which is to be detected or imaged, a laser source disposed to illuminate the RIID cell with laser radiation having a wavelength .lambda..sub.2 or wavelengths .lambda..sub.2, .lambda..sub.3 selected to ionize atoms in the cell that are in an excited state by virtue of having absorbed the scattered resonance laser radiation, and a luminescent screen at the back surface of the RIID cell which presents an image of the number and position of charged particles present in the RIID cell as a result of the ionization of the excited state atoms. The method of the invention further includes the step of initially illuminating the object to be detected or imaged with a laser having a wavelength selected such that the object will scatter laser radiation having the resonance wavelength .lambda..sub.1.

  2. Experimental Resonance Enhanced Multiphoton Ionization (REMPI) studies of small molecules

    NASA Technical Reports Server (NTRS)

    Dehmer, J. L.; Dehmer, P. M.; Pratt, S. T.; Ohalloran, M. A.; Tomkins, F. S.

    1987-01-01

    Resonance enhanced multiphoton ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of exciting opportunities for both basic and applied science. On the applied side, REMPI has great potential as an ultrasensitive, highly selective detector for trace, reactive, or transient species. On the basic side, REMPI affords an unprecedented means of exploring excited state physics and chemistry at the quantum-state-specific level. An overview of current studies of excited molecular states is given to illustrate the principles and prospects of REMPI.

  3. Parametric-Resonance Ionization Cooling in Twin-Helix.

    SciTech Connect

    V.S. Morozov, Ya.S. Derbenev, A. Afanasev, R.P. Johnson, Erdelyi. B., J.A. Maloney

    2011-09-01

    Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a highluminosity muon collider. For the implementation of PIC, we developed an epicyclic twin-helix channel with correlated optics. Wedge-shaped absorbers immediately followed by short rf cavities are placed into the twin-helix channel. Parametric resonances are induced in both planes using helical quadrupole harmonics. We demonstrate resonant dynamics and cooling with stochastic effects off using GEANT4/G4beamline. We illustrate compensation of spherical aberrations and benchmark COSY Infinity, a powerful tool for aberration analysis and compensation.

  4. Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

    NASA Astrophysics Data System (ADS)

    Flanagan, K. T.; Lynch, K. M.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Cocolios, T. E.; de Groote, R. P.; De Schepper, S.; Fedosseev, V. N.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Marsh, B. A.; Neyens, G.; Procter, T. J.; Rossel, R. E.; Rothe, S.; Strashnov, I.; Stroke, H. H.; Wendt, K. D. A.

    2013-11-01

    The magnetic moments and isotope shifts of the neutron-deficient francium isotopes Fr202-205 were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1% was measured for Fr202. The background from nonresonant and collisional ionization was maintained below one ion in 105 beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to Fr205, with a departure observed in Fr203 (N=116).

  5. Collinear resonance ionization spectroscopy of neutron-deficient francium isotopes.

    PubMed

    Flanagan, K T; Lynch, K M; Billowes, J; Bissell, M L; Budinčević, I; Cocolios, T E; de Groote, R P; De Schepper, S; Fedosseev, V N; Franchoo, S; Garcia Ruiz, R F; Heylen, H; Marsh, B A; Neyens, G; Procter, T J; Rossel, R E; Rothe, S; Strashnov, I; Stroke, H H; Wendt, K D A

    2013-11-22

    The magnetic moments and isotope shifts of the neutron-deficient francium isotopes (202-205)Fr were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1% was measured for (202)Fr. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to (205)Fr, with a departure observed in (203)Fr (N=116). PMID:24313482

  6. Anion formation in sputter ion sources by neutral resonant ionization.

    PubMed

    Vogel, J S

    2016-02-01

    Focused Cs(+) beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm(2) C(-) current density compared to the 20 μA/mm(2) from a 1 mm recess. PMID:26931912

  7. Anion formation in sputter ion sources by neutral resonant ionization

    NASA Astrophysics Data System (ADS)

    Vogel, J. S.

    2016-02-01

    Focused Cs+ beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm2 C- current density compared to the 20 μA/mm2 from a 1 mm recess.

  8. Resonant Laser Ionization Mass Spectrometry: An Alternative to AMS?

    SciTech Connect

    Wendt, Klaus; Trautmann, N.; Bushaw, Bruce A.

    2001-02-15

    Resonant laser ionization mass spectrometry (RIMS) has developed into a versatile experimental method particularly concerning applications for highly selective ultratrace analaysis. Apart from providing nearly complete isobaric suspression and high overall efficiency, the possibolility for combining optical isotpic selectivity with that of hte mass spectrometer leads to remarkable specifications. The widespread analytical potential and applicability of different techniques based on resonant laser ionization is demonstrated in investigations on stable and radioactive ultratrace isotopes with the focus on applications which require high selectivity, concerning, e.g., the noble gas isotopes, 81,85KR, PU isotopes, 89,90SR, 99Tc and 41Ca. Selective ultratrace determination of these radioisotopes proved access to a variety of fundamental research problems in environmental sciences, geo- and cosmochemistry, archaeology, and biomedicine, which previously were often an exclusive domain for accelerator mass spectrometry (AMS).

  9. Detection of single atoms by resonance ionization spectroscopy

    SciTech Connect

    Hurst, G.S.

    1986-01-01

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the RIS technique, a laser is tuned to a wavelength which will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or nonresonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms; and since detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples are given of one-atom detection, including that of the noble gases, in order to show complementarity with AMS methods. For instance, the detection of /sup 81/Kr using RIS has interesting applications for solar neutrino research, ice-cap dating, and groundwater dating. 39 refs., 7 figs., 2 tabs.

  10. A resonant ionization laser ion source at ORNL

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Stracener, D. W.

    2016-06-01

    Multi-step resonance laser ionization has become an essential tool for the production of isobarically pure radioactive ion beams at the isotope separator on-line (ISOL) facilities around the world. A resonant ionization laser ion source (RILIS) has been developed for the former Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory. The RILIS employs a hot-cavity ion source and a laser system featuring three grating-tuned and individually pumped Ti:Sapphire lasers, especially designed for stable and simple operation. The RILIS has been installed at the second ISOL production platform of former HRIBF and has successfully provided beams of exotic neutron-rich Ga isotopes for beta decay studies. This paper reports the features, advantages, limitations, and on-line and off-line performance of the RILIS.

  11. Determination of the first ionization potential of actinides by resonance ionization mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Köhler, S.; Albus, F.; Dibenberger, R.; Erdmann, N.; Funk, H.; Hasse, H.-U.; Herrmann, G.; Huber, G.; Kluge, H.-J.; Nunnemann, M.; Passler, G.; Rao, P. M.; Riegel, J.; Trautmann, N.; Urban, F.-J.

    1995-04-01

    Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential of transuranium elements. The first ionization potentials (IP) of americium and curium have been measured for the first time to IPAm=5.9738(2) and IPCm=5.9913(8) eV, respectively, using only 1012 atoms of 243Am and 248Cm. The same technique was applied to thorium, neptunium, and plutonium yielding IPTH=6.3067(2), IPNP=6.2655(2), and IPPu=6.0257(8) eV. The good agreement of our results with the literature data proves the precision of the method which was additionally confirmed by the analysis of Rydberg seris of americium measured by RIMS.

  12. Calculating Relative Ionization Probabilities of Plutonium for Resonance Ionization Mass Spectrometry to Support Nuclear Forensic Investigations

    NASA Astrophysics Data System (ADS)

    Lensegrav, Craig; Smith, Craig; Isselhardt, Brett

    2015-03-01

    Ongoing work seeks to apply the technology of Resonance Ionization Mass Spectrometry (RIMS) to problems related to nuclear forensics and, in particular, to the analysis and quantification of debris from nuclear detonations. As part of this effort, modeling and simulation methods are being applied to analyze and predict the potential for ionization by laser excitation of isotopes of both uranium and plutonium. Early work focused on the ionization potential of isotopes of uranium, and the present effort has expanded and extended the previous work by identifying and integrating new data for plutonium isotopes. In addition to extending the effort to this important new element, we have implemented more accurate descriptions of the spatial distribution of the laser beams to improve the accuracy of model predictions compared with experiment results as well as an ability to readily incorporate new experimental data as they become available. The model is used to estimate ionization cross sections and to compare relative excitation on two isotopes as a function of wavelength. This allows the study of sensitivity of these measurements to fluctuations in laser wavelength, irradiance, and bandwidth. We also report on initial efforts to include predictions of americium ionization probabilities into our modeling package. I would like to thank my co-authors, Gamani Karunasiri and Fabio Alves. My success is a product of their support and guidance.

  13. Progress of resonant ionization laser ion source development at GANIL

    SciTech Connect

    Henares, J. L. Huguet, Y.; Lecesne, N.; Leroy, R.; Osmond, B.; Sjödin, A. M.; Kron, T.; Schneider, F.; Wendt, K.

    2014-02-15

    SPIRAL2 (Système de Production d’Ions Radioactifs Accélérés en Ligne) is a research facility under construction at GANIL (Grand Accélérateur National d’Ions Lourds) for the production of radioactive ion beams by isotope separation on-line methods and low-energy in-flight techniques. A resonant ionization laser ion source will be one of the main techniques to produce the radioactive ion beams. GISELE (GANIL Ion Source using Electron Laser Excitation) is a test bench developed to study a fully operational laser ion source available for Day 1 operations at SPIRAL2 Phase 2. The aim of this project is to find the best technical solution which combines high selectivity and ionization efficiency with small ion beam emittance and stable long term operation. Latest results about the new ion source geometry will be presented.

  14. Resonance Ionization Mass Spectrometry System for Measurement of Environmental Samples

    NASA Astrophysics Data System (ADS)

    Pibida, L.; McMahon, C. A.; Nörtershäuser, W.; Bushaw, B. A.

    2002-10-01

    A resonance ionization mass spectrometry (RIMS) system has been developed at the National Institute of Standards and Technology (NIST) for sensitive and selective determination of radio-cesium in the environment. The overall efficiency was determined to be 4×10-7 with a combined (laser and mass spectrometer) selectivity of 108 for both 135Cs and 137Cs with respect to 133Cs. RIMS isotopic ratio measurements of 135Cs/ 137Cs were performed on a nuclear fuel burn-up sample and compared to measurements on a similar system at Pacific Northwest National Laboratory (PNNL) and to conventional thermal ionization mass spectrometry (TIMS). Results of preliminary RIMS investigations on a freshwater lake sediment sample are also discussed.

  15. Resonance ionization of holmium for ion implantation in microcalorimeters

    NASA Astrophysics Data System (ADS)

    Schneider, F.; Chrysalidis, K.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Haas, R.; Kieck, T.; Mokry, C.; Naubereit, P.; Schmidt, S.; Wendt, K.

    2016-06-01

    The determination of the electron neutrino mass by calorimetric measurement of the 163 Ho electron capture spectrum requires ultra-pure samples. Several collaborations, like ECHo or HOLMES, intend to employ microcalorimeters into which 163 Ho is implanted as an ion beam. This makes a selective and additionally very efficient ion source for holmium mandatory. For this purpose, laser resonance ionization of stable holmium 165 Ho was studied, using a three step excitation scheme driven by pulsed Ti:sapphire lasers. Five measurements with sample sizes of 1014 and 1015 atoms were performed for the efficiency investigation. In average, an excellent ionization efficiency of 32(5) % could be shown, demonstrating the suitability for ion beam implantation.

  16. Plasma induced by resonance enhanced multiphoton ionization in inert gas

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2007-12-15

    We present a detailed model for the evolution of resonance enhanced multiphoton ionization (REMPI) produced plasma during and after the ionizing laser pulse in inert gas (argon, as an example) at arbitrary pressures. Our theory includes the complete process of the REMPI plasma generation and losses, together with the changing gas thermodynamic parameters. The model shows that the plasma expansion follows a classical ambipolar diffusion and that gas heating results in a weak shock or acoustic wave. The gas becomes involved in the motion not only from the pressure gradient due to the heating, but also from the momentum transfer from the charged particles to gas atoms. The time dependence of the total number of electrons computed in theory matches closely with the results of coherent microwave scattering experiments.

  17. Detection of arsenic by resonance ionization mass spectrometry

    SciTech Connect

    Nogar, N.; Anderson, J.; Allen, T.; Smith, C.

    1996-03-01

    This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The development of sensitive analytical techniques for environmental analysis is a problem of immediate interest. Waste residues containing heavy metals such as chromium, lead and arsenic are particular problems due to their widespread usage and sometime incomplete recovery or inadequate storage. The objective of this project was to apply resonance ionization mass spectrometry (RIMS) to the detection of trace levels of arsenic.

  18. Ion cyclotron resonance heating systems upgrade toward high power and CW operations in WEST

    SciTech Connect

    Hillairet, Julien Mollard, Patrick; Bernard, Jean-Michel; Argouarch, Arnaud; Berger-By, Gilles; Charabot, Nicolas; Colas, Laurent; Delaplanche, Jean-Marc; Ekedahl, Annika; Fedorczak, Nicolas; Ferlay, Fabien; Goniche, Marc; Hatchressian, Jean-Claude; Helou, Walid; Jacquot, Jonathan; Joffrin, Emmanuel; Litaudon, Xavier; Lombard, Gilles; Magne, Roland; Patterlini, Jean-Claude; and others

    2015-12-10

    The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion cyclotron resonance heating antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the V{sub r}/V{sub f} and SHAD systems.

  19. Ion cyclotron resonance heating systems upgrade toward high power and CW operations in WEST

    NASA Astrophysics Data System (ADS)

    Hillairet, Julien; Mollard, Patrick; Zhao, Yanping; Bernard, Jean-Michel; Song, Yuntao; Argouarch, Arnaud; Berger-By, Gilles; Charabot, Nicolas; Chen, Gen; Chen, Zhaoxi; Colas, Laurent; Delaplanche, Jean-Marc; Dumortier, Pierre; Durodié, Frédéric; Ekedahl, Annika; Fedorczak, Nicolas; Ferlay, Fabien; Goniche, Marc; Hatchressian, Jean-Claude; Helou, Walid; Jacquot, Jonathan; Joffrin, Emmanuel; Litaudon, Xavier; Lombard, Gilles; Maggiora, Riccardo; Magne, Roland; Milanesio, Daniele; Patterlini, Jean-Claude; Prou, Marc; Verger, Jean-Marc; Volpe, Robert; Vulliez, Karl; Wang, Yongsheng; Winkler, Konstantin; Yang, Qingxi; Yuan, Shuai

    2015-12-01

    The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion cyclotron resonance heating antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the Vr/Vf and SHAD systems.

  20. Progress on muon parametric-resonance ionization cooling channel development

    SciTech Connect

    V.S. Morozov, Ya.S. Derbenev, A. Afanasev, K.B. Beard, R.P. Johnson, B. Erdelyi, J.A. Maloney

    2012-07-01

    Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel's period length. We observe a parasitic parametric resonance naturally occurring in the channel's horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC.

  1. Multiple overlapping resonance treatment in electron-cadmium ionization

    NASA Astrophysics Data System (ADS)

    Tabanli, M. M.; Peacher, J. L.; Madison, D. H.

    2001-05-01

    The effect of autoionizing resonances on ionization has been studied since the historic work of Fano. We have calculated triple differential cross sections for electron-cadmium scattering using a multiple overlapping resonance treatment. Our (DWBA) results are compared to the non-overlapping resonance treatment of Madison et al.(D. H. Madison, V. D. Kravtsov, J. B. Dent, and M. Wilson Phys. Rev. A) 56, 1983 (1997). and coincidence measurements made by Martin et al.(N. L. S. Martin, R. P. Bauman, and M. Wilson Phys. Rev. A) 57, 1827 (1998). at an incident electron energy of 150 eV. The ejected electron energy was near 3.5 eV and measurements were made for scattering angles between 2 and 15 degrees. Last year we presented preliminary results for the scattering angles of 2 and 3 degrees. We have now reformulated the phase of the mixing coefficients and the transition amplitude to include spin explicitly. The new treatment gives significantly better results for scattering angles larger than 6 degrees. This new approach also gives a sharp minimun and maximum near the third resonance.

  2. Resonance Ionization Instability in HF and Microwave Discharges

    NASA Astrophysics Data System (ADS)

    Dvinin, Sergey; Dovzhenko, Vitaliy

    2013-09-01

    For the first time ionization instability of HF plasma has been described in. Later it has been shown that in the spatially limited low pressure microwave discharge the given instability leads not only to change plasma structure, but to appearance of resonances at electron densities, when the size of plasma becomes multiple to some number of half waves of the standing surface wave, exciting on plasma boundary. Evolution of electron density perturbation is defined by two processes - negative feedback owing to a total current continuity (as in striations) and positive one due to excitation of a wave, which is close to a resonance. In the given work the theory has been improved with accounting of both processes that has allowed to reach better coincidence with experiment. In addition, the general theory of ionization instability has been developed. Application of the model to CCP HF (100 MHz and higher) discharge with large electrodes has shown that excitation of the instability accompanied by surface waves, propagating along plasma-sheath-electrodes interface, is possible.

  3. Determination of a three-step excitation and ionization scheme for resonance ionization and ultratrace analysis of Np-237

    NASA Astrophysics Data System (ADS)

    Raeder, S.; Stöbener, N.; Gottwald, T.; Passler, G.; Reich, T.; Trautmann, N.; Wendt, K.

    2011-03-01

    The long-lived radio isotope 237Np is generated within the nuclear fuel cycle and represents a major hazard in the final disposal of nuclear waste. Related geochemical research requires sensitive methods for the detection of ultratrace amounts of neptunium in environmental samples. Resonance ionization mass spectrometry (RIMS) has proven to be one of the most sensitive methods for the detection of plutonium. A precondition for the application of RIMS to ultratrace analysis of neptunium is the knowledge of an efficient and selective scheme for optical excitation and ionization. Therefore, a multitude of medium to high-lying atomic levels in neptunium was located by applying in-source resonance ionization spectroscopy. By using excitation via six previously known first excited, intermediate levels of odd parity, a set of twelve so far unknown high-lying levels of even parity were identified and studied further for their suitability in resonant excitation/ionization schemes. Autoionizing resonances for efficient ionization of neptunium atoms were subsequently accessed spectroscopically. Altogether five resonance ionization schemes were investigated and characterized concerning their saturation behavior and relative efficiency. Applying a calibrated sample, an overall efficiency of 0.3 % was determined.

  4. Resonance ionization mass spectrometric study of the promethium/samarium isobaric pair

    SciTech Connect

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1988-01-01

    Samarium daughters are problematic in isotope ratio measurements of promethium because they are isobaric. Resonance ionization mass spectrometry was utilized to circumvent this problem. An ionization selectivity factor of at least 1000:1 has been measured for promethium over samarium at 584.6 nm. Resonance ionization spectra have been recorded for both elements over the 528-560 and 580-614 nm wavelength ranges.

  5. Laser resonance ionization scheme development for tellurium and germanium at the dual Ti:Sa-Dye ISOLDE RILIS

    NASA Astrophysics Data System (ADS)

    Day Goodacre, T.; Fedorov, D.; Fedosseev, V. N.; Forster, L.; Marsh, B. A.; Rossel, R. E.; Rothe, S.; Veinhard, M.

    2016-09-01

    The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source laser resonance ionization spectroscopy, a transition to a new autoionizing state of tellurium was discovered and applied as part of a three-step, three-resonance, photo-ionization scheme. In a second study, a three-step, two-resonance, photo-ionization scheme for germanium was developed and the ionization efficiency was measured at ISOLDE. This work increases the range of ISOLDE RILIS ionized beams to 31 elements. Details of the spectroscopy studies are described and the new ionization schemes are summarized.

  6. Double-electron above-threshold ionization resonances as interference phenomena

    NASA Astrophysics Data System (ADS)

    Armstrong, G. S. J.; Parker, J. S.; Taylor, K. T.

    2012-11-01

    We present high-accuracy full-dimensionality calculations of total kinetic energy spectra of doubly-ionized helium at 195 nm. We find that the resonances in these spectra have their origins as interference phenomena.

  7. Relativistic effects on giant resonances in electron-impact double ionization

    SciTech Connect

    Pindzola, M.S.

    1987-06-01

    The electron-impact double-ionization cross section for Fr/sup +/ is calculated in the distorted-wave Born approximation. A giant resonance in the 5d subshell ionization-autoionization contribution to the cross section is found to be quite sensitive to changes in the double-well potential caused by relativistic effects on bound-state wave functions.

  8. Detection of undistorted continuous wave (CW) electron paramagnetic resonance (EPR) spectra with non-adiabatic rapid sweep (NARS) of the magnetic field

    PubMed Central

    Kittell, Aaron W.; Camenisch, Theodore G.; Ratke, Joseph J.; Sidabras, Jason W.; Hyde, James S.

    2011-01-01

    A continuous wave (CW) electron paramagnetic resonance (EPR) spectrum is typically displayed as the first harmonic response to the application of 100 kHz magnetic field modulation, which is used to enhance sensitivity by reducing the level of 1/f noise. However, magnetic field modulation of any amplitude causes spectral broadening and sacrifices EPR spectral intensity by at least a factor of two. In the work presented here, a CW rapid-scan spectroscopic technique that avoids these compromises and also provides a means of avoiding 1/f noise is developed. This technique, termed non-adiabatic rapid sweep (NARS) EPR, consists of repetitively sweeping the polarizing magnetic field in a linear manner over a spectral fragment with a small coil at a repetition rate that is sufficiently high that receiver noise, microwave phase noise, and environmental microphonics, each of which has 1/f characteristics, are overcome. Nevertheless, the rate of sweep is sufficiently slow that adiabatic responses are avoided and the spin system is always close to thermal equilibrium. The repetitively acquired spectra from the spectral fragment are averaged. Under these conditions, undistorted pure absorption spectra are obtained without broadening or loss of signal intensity. A digital filter such as a moving average is applied to remove high frequency noise, which is approximately equivalent in bandwidth to use of an integrating time constant in conventional field modulation with lock-in detection. Nitroxide spectra at L- and X-band are presented. PMID:21741868

  9. Resonance overlap criterion for H atom ionization by circularly polarized microwave fields

    SciTech Connect

    Sacha, K.; Zakrzewski, J.

    1997-01-01

    The threshold for H atom ionization by circularly polarized microwave fields is discussed within the classical mechanics framework for high microwave frequencies. The Chirikov resonance overlap criterion predictions are compared with estimates obtained adopting the renormalization method. It is shown that the ionization threshold is highly sensitive to the helicity of microwaves. Among all possible initial electronic orbits, those of medium eccentricity are the first to ionize. The results obtained indicate that collisions with the nucleus play a negligible role for the onset of ionization. {copyright} {ital 1997} {ital The American Physical Society}

  10. [Laser-induced isotopic discrimination effect in laser resonance ionization process of lead atom].

    PubMed

    Wang, Xin-Shun; Li, Ying; Dai, Lin; Zheng, Rong-Er

    2008-07-01

    Isotope ratio measurements have been increasingly used in geochemistry, geochronology, cosmos chemistry and environmental science. Precise and accurate isotope ratio measurements are an important task in many applications such as the determination of isotope variations in geological and cosmic samples. Due to its high sensitivity, high ionization efficiency and high element selectivity, laser resonance ionization spectroscopy has nowadays become one of the key techniques, including isotope ratio measurements and trace amount analyses. Because of the isotope shifts and hyperfine structure, there is laser-induced isotopic discrimination effect in the process of laser resonance ionization. The different isotope ionization efficiency can affect precise and accurate measurement of isotope ratios. In the present paper, the dependences of the laser-induced isotopic discrimination effect on some of the laser parameters were studied by theoretical methods. Based on the numerical simulation of the population rate equations, laser-induced isotopic discrimination effect of lead isotopes was studied, by calculating laser resonance ionization transition "6s2 6p23 P0-6s2 6p7 s3 P1(0) --> ionization". The population rate equations was approximated considering some factors which affect the probability of laser resonance transition such as spectral lines width of laser and atom, isotope shifts and hyperfine structure. According to the approximated population rate equations, "1+1" laser resonant ionization process was employed to calculate the ionization probability of lead isotopes by means of computer simulation. The dependences of laser-induced isotopic discrimination effect on the laser parameters, such as laser central wavelength, bandwidth and intensity were investigated. The calculated results show that the laser-induced isotopic discrimination effect of lead isotopes could be almost eliminated by operating at optimized wavelength and could be lessened by using wide band laser

  11. The efficiencies of resonant and nonresonant multiphoton ionization in the femtosecond region.

    PubMed

    Kouno, Hiroaki; Imasaka, Totaro

    2016-09-21

    Ionization efficiency in mass spectrometry was examined for three types of molecules under different ionization schemes, i.e., resonant/nonresonant and two-photon/three-photon ionization, using an ultraviolet (UV) femtosecond laser at different wavelengths, pulse energies, and pulse widths. The efficiency of nonresonant ionization could be improved substantially by decreasing the laser pulse width. The effect of resonance was minimal when an ultrashort optical pulse of less than 100 fs was employed for ionization in the UV region. Three-photon ionization was less efficient than two-photon ionization, but the difference was not significant at shorter pulse widths in the femtosecond region. Although the excess energy can be decreased by optimizing the laser wavelength in the case of nonresonant ionization, fragmentation was not suppressed in the cases studied here. However, fragmentation was drastically suppressed when the laser pulse width was decreased. Thus, this approach of using an ultrashort optical pulse would provide a new tool for soft ionization and then for more reliable identification of an analyte.

  12. Mass resolved resonance ionization spectroscopy of combustion radicals

    SciTech Connect

    Not Available

    1992-06-23

    This report discusses the following topics: REMPI spectroscopy of HCO and DCO; Rempi spectroscopy of the ethynyl radical; REMPI spectroscopy of new electronic states of C{sub 2}; and a flame sampling laser ionization mass spectrometer.

  13. Muon Tracking Studies in a Skew Parametric Resonance Ionization Cooling Channel

    SciTech Connect

    Sy, Amy; Afanaciev, Andre; Derbenev, Yaroslav S.; Johnson, Rolland; Morozov, Vasiliy

    2015-09-01

    Skew Parametric-resonance Ionization Cooling (SPIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. A first practical implementation of the magnetic field components required in the SPIC channel is modeled in MADX. Dynamic features of the coupled correlated optics with and without induced parametric resonance are presented and discussed.

  14. A CW CO 2 laser using a high-voltage Dc-dc converter with resonant inverter and Cockroft-Walton multiplier

    NASA Astrophysics Data System (ADS)

    Chung, Hyun-Ju

    2006-11-01

    I propose a high-voltage Dc-dc converter for a CW (continuous wave) CO 2 laser system using a current resonant half-bridge inverter and a Cockcroft-Walton circuit. This high-voltage power supply includes a two-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the secondary transformer is applied to the voltage multiplier. It is highly efficient because of the reduced amount of switching losses by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step-up secondary transformer combined with the Cockroft-Walton circuit. I obtained a maximum laser output power of 44 W, a maximum system efficiency of over 16%, and the stability of laser output power of about 4.6% in this laser system.

  15. Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

    SciTech Connect

    Isselhardt, Brett H.

    2011-09-01

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

  16. Influence of resonant charge exchange on the viscosity of partially ionized plasma in a magnetic field

    SciTech Connect

    Zhdanov, V. M. Stepanenko, A. A.

    2013-12-15

    The influence of resonant charge exchange for ion-atom interaction on the viscosity of partially ionized plasma embedded in the magnetic field is investigated. The general system of equations used to derive the viscosity coefficients for an arbitrary plasma component in the 21-moment approximation of Grad’s method is presented. The expressions for the coefficients of total and partial viscosities of a multicomponent partially ionized plasma in the magnetic field are obtained. As an example, the coefficients of the parallel and transverse viscosities for the ionic and neutral components of the partially ionized hydrogen plasma are calculated. It is shown that the account for resonant charge exchange can lead to a substantial change of the parallel and transverse viscosity of the plasma components in the region of low degrees of ionization on the order of 0.1.

  17. Resonant and nonresonant multiphoton ionization processes in the mass spectrometry of explosives.

    PubMed

    Hamachi, Akifumi; Okuno, Tomoya; Imasaka, Tomoko; Kida, Yuichiro; Imasaka, Totaro

    2015-03-01

    Multiphoton ionization processes were studied for three types of explosives using a line-tunable ultraviolet femtosecond laser. When peroxides such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) were ionized through a nonresonant two-photon process, a molecular ion was dominantly observed by reducing the excess energy remaining in the ion. However, an aromatic nitro compound such as 2,4,6-trinitrotoluene (TNT) produced large signals arising from molecular and fragment ions by resonant two-photon ionization. In addition, only fragment ions were produced from a nonaromatic nitro compound such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), even when a resonant two-photon ionization process was employed, suggesting that a further reduction in excess energy would be necessary if a molecular ion were to be observed. PMID:25622138

  18. In-source spectroscopy on astatine and radium for resonant laser ionization

    NASA Astrophysics Data System (ADS)

    Raeder, Sebastian; Lassen, Jens; Heggen, Henning; Teigelhöfer, Andrea

    2014-06-01

    At on-line isotope separator facilities, rare isotopes of radioactive elements such as astatine, radium or polonium are demanded for fundamental research on nuclear structure. These elements are generally suitable for a resonance ionization laser ion source, but more data on the atomic structure is necessary to develop efficient laser ionization schemes. Due to the missing stable reference isotopes spectroscopic investigation of the atomic structure can only be performed during on-line operation. At the Isotope Separator and ACcelerator (ISAC) facility at TRIUMF, the elements astatine and radium were investigated by in-source laser spectroscopy to optimize the laser ionization efficiency. For astatine, laser spectroscopy was performed to search for high lying bound states as well as for auto-ionizing resonances. This led to the identification of four new high lying bound states of odd parity, while no auto-ionizing resonances were observed in the investigated region. Furthermore, the feasibility and the impact of laser ionization on the yield of radium isotopes was investigated using an activated target after proton irradiation.

  19. Resonance-mediated atomic ionization dynamics induced by ultraintense x-ray pulses

    NASA Astrophysics Data System (ADS)

    Ho, Phay J.; Kanter, E. P.; Young, L.

    2015-12-01

    We describe the methodology of our recently developed Monte Carlo rate equation (MCRE) approach, which systematically incorporates bound-bound resonances to model multiphoton ionization dynamics induced by high-fluence, high-intensity x-ray free-electron laser (XFEL) pulses. These resonances are responsible for ionization far beyond that predicted by the sequential single photon absorption model and are central to a quantitative understanding of atomic ionization dynamics in XFEL pulses. We also present calculated multiphoton ionization dynamics for Kr and Xe atoms in XFEL pulses for a variety of conditions, to compare the effects of bandwidth, pulse duration, pulse fluence, and photon energy. This comprehensive computational investigation reveals areas in the photon energy-pulse fluence landscape where resonances are critically important. We also uncover a mechanism, preservation of inner-shell vacancies (PIVS), whereby radiation damage is enhanced at higher XFEL intensities and identify the sequence of core-outer-Rydberg, core-valence, and core-core resonances encountered during multiphoton x-ray ionization.

  20. Laser-induced resonance states as dynamic suppressors of ionization in high-frequency short pulses

    SciTech Connect

    Barash, Danny; Orel, Ann E.; Baer, Roi

    2000-01-01

    An adiabatic-Floquet formalism is used to study the suppression of ionization in short laser pulses. In the high-frequency limit the adiabatic equations involve only the pulse envelope where transitions are purely ramp effects. For a short-ranged potential having a single-bound state we show that ionization suppression is caused by the appearance of a laser-induced resonance state, which is coupled by the pulse ramp to the ground state and acts to trap ionizing flux. (c) 1999 The American Physical Society.

  1. Resonance ionization spectroscopy: counting noble-gas atoms

    SciTech Connect

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-06-01

    New work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions) is reported. When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. It is shown that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective.

  2. Photodissociation resonances of jet-cooled NO{sub 2} at the dissociation threshold by CW-CRDS

    SciTech Connect

    Dupré, Patrick

    2015-05-07

    Around 398 nm, the jet-cooled-spectrum of NO{sub 2} exhibits a well identified dissociation threshold (D{sub 0}). Combining the continuous-wave absorption-based cavity ringdown spectroscopy technique and laser induced fluorescence detection, an energy range of ∼25 cm{sup −1} is analyzed at high resolution around D{sub 0}. In addition to the usual molecular transitions to long-lived energy levels, ∼115 wider resonances are observed. The position, amplitude, and width of these resonances are determined. The resonance width spreads from ∼0.006 cm{sup −1} (i.e., ∼450 ps) to ∼0.7 cm{sup −1} (∼4 ps) with large fluctuations. The identification of at least two ranges of resonance width versus the excess energy can be associated with the opening of the dissociation channels NO{sub 2}→NO(X {sup 2}Π{sub 1/2}, v=0, J=1/2)+O({sup 3}P{sub 2}) and NO{sub 2}→NO(X {sup 2}Π{sub 1/2}, v=0, J=3/2)+O({sup 3}P{sub 2}). This analysis corroborates the existence of loose transition states close to the dissociation threshold as reported previously and in agreement with the phase space theory predictions as shown by Tsuchiya’s group [Miyawaki et al., J. Chem. Phys. 99, 254–264 (1993)]. The data are analyzed in the light of previously reported frequency- and time-resolved data to provide a robust determination of averaged unimolecular dissociation rate coefficients. The density of reactant levels deduced (ρ{sub reac} ∼ 11 levels/cm{sup −1}) is discussed versus the density of transitions, the density of resonances, and the density of vibronic levels.

  3. Epicyclic Helical Channels for Parametric Resonance Ionization Cooling

    SciTech Connect

    Andrei Afanaciev, Alex Bogacz, Yaroslav Derbenev, Kevin Beard, Valentin Ivanov, Rolland Johnson, Guimei Wang, Katsuya Yonehara

    2009-05-01

    In order to achieve cooling of muons in addition to 6D helical cooling channel (HCC) [1], we develop a technique based on a parametric resonance. The use of parametric resonances requires alternating dispersion, minimized at locations of thin absorbers, but maximized in between in order to compensate for chromatic aberrations [2]. These solutions can be combined in an Epicyclic Helical Cooling Channel (EHCC) that meets requirements of alternating dispersion of beam periodic orbit with best conditions for maintenance of stable beam transport in a continuous solenoid-type field [3]. We discuss here basic features and new simulation results for EHCC.

  4. Atomic vapor laser isotope separation using resonance ionization

    SciTech Connect

    Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J.; Paisner, J.; Solarz, R.; Worden, E.

    1986-09-01

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.

  5. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    SciTech Connect

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-14

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O₂/N₂ and O₂/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O₂ 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  6. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-01

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O2/N2 and O2/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O2 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  7. Modeling of the initiation and evolution of a laser-ionized column in the lower atmosphere - 314.5 nm wavelength resonant multiphoton ionization of naturally occurring argon

    NASA Technical Reports Server (NTRS)

    Fetzer, G. J.; Stockley, J. E.

    1992-01-01

    A 3+1 resonant multiphoton ionization process in naturally occurring argon is studied at 314.5 nm as a candidate for providing a long ionized channel through the atmosphere. Results are presented which indicate peak electron densities up to 10 exp 8/cu cm can be created using laser intensities on the order of 10 exp 8 W/sq cm.

  8. A Combined Laser Ablation-Resonance Ionization Mass Spectrometer for Planetary Surface Geochronology

    NASA Technical Reports Server (NTRS)

    Cardell, G.; Taylor, M. E.; Stewart, B. W.; Capo, R. C.; Crown, D. A.

    2002-01-01

    Progress in the development of an instrument for direct geochronologic measurements on rocks in situ will be described. The instrument integrates laser ablation sampling, resonance ionization, and mass spectrometry to directly measure concentrations of the Rb-Sr isotope system. Additional information is contained in the original extended abstract.

  9. Skew-Quad Parametric-Resonance Ionization Cooling: Theory and Modeling

    SciTech Connect

    Afanaciev, Andre; Derbenev, Yaroslav S.; Morozov, Vasiliy; Sy, Amy; Johnson, Rolland P.

    2015-09-01

    Muon beam ionization cooling is a key component for the next generation of high-luminosity muon colliders. To reach adequately high luminosity without excessively large muon intensities, it was proposed previously to combine ionization cooling with techniques using a parametric resonance (PIC). Practical implementation of PIC proposal is a subject of this report. We show that an addition of skew quadrupoles to a planar PIC channel gives enough flexibility in the design to avoid unwanted resonances, while meeting the requirements of radially-periodic beam focusing at ionization-cooling plates, large dynamic aperture and an oscillating dispersion needed for aberration corrections. Theoretical arguments are corroborated with models and a detailed numerical analysis, providing step-by-step guidance for the design of Skew-quad PIC (SPIC) beamline.

  10. On-Line Commissioning of the HRIBF Resonant Ionization Laser Ion Source

    SciTech Connect

    Liu, Yuan; Jost, Carola U; Mendez, II, Anthony J; Stracener, Daniel W; Williams, Cecil L; Madurga, M; Miernik, Krzysztof A; Miller, D.; Padgett, S; Paulauskas, Stanley V; Gross, Carl J; Grzywacz, Robert Kazimierz; Rykaczewski, Krzysztof Piotr; Wolinska-Cichocka, Marzena

    2013-01-01

    A highly-selective resonant ionization laser ion source has been successfully commissioned at the Holifield Radioactive Ion Beam Facility, Oak Ridge National Laboratory, for the production of pure beams of short-lived nuclei for spectroscopic studies. The laser ion source provided beams of neutron-rich Ga isotopes to the Low-energy Radioactive Ion Beam Spectroscopy Station for beta decay measurements. The radioactive Ga isotopes were produced by 50-MeV proton induced fission of 238U and ionized by laser radiation using a two-step resonant ionization scheme. Isobarically pure 83Ga, 85Ga, and 86Ga beams were delivered to the experiment at approximate rates of 12000 ions/s, 100 ions/s, and 3 ions/s, respectively.

  11. Resonantly enhanced multiphoton ionization under XUV FEL radiation: a case study of the role of harmonics

    NASA Astrophysics Data System (ADS)

    Nikolopoulos, G. M.; Lambropoulos, P.

    2015-12-01

    We provide a detailed quantitative study of the possible role of a small admixture of harmonics on resonant two-photon ionization. The motivation comes from the occasional presence of 2nd and 3rd harmonics in FEL radiation. We obtain the dependence of ionic yields on the intensity of the fundamental, the percentage of 2nd harmonic and the detuning of the fundamental from resonance. Having examined the cases of one and two intermediate resonances, we arrive at results of general validity and global behaviour, showing that even a small amount of harmonic may seem deceptively innocuous.

  12. Doubly resonant three-photon double ionization of Ar atoms induced by an EUV free-electron laser

    SciTech Connect

    Gryzlova, E. V.; Ma, Ri; Fukuzawa, H.; Motomura, K.; Yamada, A.; Ueda, K.; Grum-Grzhimailo, A. N.; Strakhova, S. I.; Kabachnik, N. M.; Rouzee, A.; Hundermark, A.; Vrakking, M. J. J.; Johnsson, P.; Nagaya, K.; Yase, S.; Mizoguchi, Y.; Yao, M.; Nagasono, M.; Tono, K.; Yabashi, M.; and others

    2011-12-15

    A mechanism for three-photon double ionization of atoms by extreme-ultraviolet free-electron laser pulses is revealed, where in a sequential process the second ionization step, proceeding via resonant two-photon ionization of ions, is strongly enhanced by the excitation of ionic autoionizing states. In contrast to the conventional model, the mechanism explains the observed relative intensities of photoelectron peaks and their angular dependence in three-photon double ionization of argon.

  13. Identification of four rotamers of m-methoxystyrene by resonant two-photon ionization and mass analyzed threshold ionization spectroscopy

    SciTech Connect

    Xu, Yanqi; Tzeng, Sheng Yuan; Takahashi, Kaito; Shivatare, Vidya; Zhang, Bing; Tzeng, Wen Bih

    2015-03-28

    We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S{sub 1}← S{sub 0} electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm{sup −1}, and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm{sup −1} for these isomeric species. Most of the observed active vibrations in the electronically excited S{sub 1} and cationic ground D{sub 0} states involve in-plane ring deformation and substituent-sensitive bending motions. It is found that the relative orientation of the methoxyl with respect to the vinyl group does not influence the vibrational frequencies of the ring-substituent bending modes. The two dimensional potential energy surface calculations support our experimental finding that the isomerization is restricted in the S{sub 1} and D{sub 0} states.

  14. Identification of four rotamers of m-methoxystyrene by resonant two-photon ionization and mass analyzed threshold ionization spectroscopy.

    PubMed

    Xu, Yanqi; Tzeng, Sheng Yuan; Shivatare, Vidya; Takahashi, Kaito; Zhang, Bing; Tzeng, Wen Bih

    2015-03-28

    We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S1← S0 electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm(-1), and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm(-1) for these isomeric species. Most of the observed active vibrations in the electronically excited S1 and cationic ground D0 states involve in-plane ring deformation and substituent-sensitive bending motions. It is found that the relative orientation of the methoxyl with respect to the vinyl group does not influence the vibrational frequencies of the ring-substituent bending modes. The two dimensional potential energy surface calculations support our experimental finding that the isomerization is restricted in the S1 and D0 states.

  15. High efficiency resonance ionization of palladium with Ti:sapphire lasers

    NASA Astrophysics Data System (ADS)

    Kron, T.; Liu, Y.; Richter, S.; Schneider, F.; Wendt, K.

    2016-09-01

    This work presents the development and testing of highly efficient excitation schemes for resonance ionization of palladium. To achieve the highest ionization efficiencies, a high-power, high repetition rate Ti:sapphire laser system was used and 2-step, 3-step and 4-step schemes were investigated and compared. Starting from different excited steps, the frequencies of the final ionization steps were tuned across the full accessible spectral range of the laser system, revealing several autoionizing Rydberg series, which converge towards the energetically higher lying state 4{{{d}}}9{}2{{{D}}}3/2 of the Pd+ ion ground state configuration. Through proper choice of these excitation steps, we developed a highly efficient, fully resonant 3-step excitation scheme, which lead to overall efficiencies of 54.3(1.4) % and 59.7(2.1) %, measured at two independent mass separator setups. To our knowledge, these are presently the highest efficiency values ever achieved with a resonance ionization laser ion source.

  16. Resonance ionization laser ion sources for on-line isotope separators (invited).

    PubMed

    Marsh, B A

    2014-02-01

    A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented. PMID:24593628

  17. Resonance ionization laser ion sources for on-line isotope separators (invited)

    SciTech Connect

    Marsh, B. A.

    2014-02-15

    A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented.

  18. Resonance ionization laser ion sources for on-line isotope separators (invited).

    PubMed

    Marsh, B A

    2014-02-01

    A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented.

  19. Improving precision in resonance ionization mass spectrometry : influence of laser bandwidth in uranium isotope ratio measurements.

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Knight, K. B.; Pellin, M. J.; Hutcheon, I. D.; Prussin, S. G.

    2011-03-01

    The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios by resonance ionization mass spectrometry (RIMS) to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a three-color, three-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from 10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation.

  20. PRODUCTION OF HIGH-POWER CW UV BY RESONANT FREQUENCY QUADRUPLING OF A ND:YLF LASER.

    SciTech Connect

    KUCZEWSKI,A.J.

    1999-01-28

    We have constructed a single ring to resonantly double an 18 watt Nd:YLF mode-locked laser and re-double the stored green to produce over 4 watts of power in the ultra-violet (UV). This laser is used to produce a beam of 470 MeV gamma-rays by Compton backscattering the laser beam from 2.8 GeV electrons stored in a synchrotron. Achieving high luminosity of the colliding beams requires very good mode quality and beam stability at the intersection point 22 meters from the laser. The ring consists of six mirrors, with two 25 cm radius of curvature mirrors enclosing each nonlinear crystal. The drive laser is a lamp pumped Nd:YLF with a 50 ps bunch length at 76 MHz. A pointing stabilizer servo has been constructed as part of the infrared (IR) mode matching telescope. The IR to green conversion is accomplished in a 15 mm long non-critically phased matched LB0 crystal located at a 40 micron waist, with an IR conversion efficiency of 70%. A stable, nearly diffraction limited W beam of up to 4.2 watts is generated in a BBO crystal in the green storage ring. The output power is relatively independent of the efficiency of the LB0 and BBO crystals. This fact makes it possible to reduce the amount of non-TEM{sub 00} modes created by walk-off of the UV by using relatively thin BBO crystals. At present, however, the lower bound on the BBO thickness is limited by the loss of conversion efficiency at high power.

  1. Production of high-power CW UV by resonant frequency quadrupling of a Nd:YLF laser

    SciTech Connect

    Kuczewski, A.J.; Thorn, C.E.; Matone, G.; Giordano, G.

    1999-06-01

    The authors have constructed a single ring to resonantly double an 18 watt Nd:YLF mode-locked laser and re-double the stored green to produce over 4 watts of power in the ultra-violet (UV). This laser is used to produce a beam of 470 MeV gamma-rays by Compton backscattering the laser beam from 2.8 GeV electrons stored in a synchrotron. Achieving high luminosity of the colliding beams requires very good mode quality and beam stability at the intersection point 22 meters from the laser. The ring consists of six mirrors, with two 25 cm radius of curvature mirrors enclosing each nonlinear crystal. The drive laser is a lamp-pumped Nd:YLF with a 50 ps bunch length at 76 MHz. A pointing stabilizer servo has been constructed as part of the infrared (IR) mode matching telescope. The IR to green conversion is accomplished in a 15 mm long non-critically phased matched LBO crystal located at a 40 micron waist, with an IR conversion efficiency of 70%. A stable, nearly diffraction limited UV beam of up to 4.2 watts is generated in a BBO crystal in the green storage ring. The output power is relatively independent of the efficiency of the LBO and BBO crystals. This fact makes it possible to reduce the amount of non-TEM{sub 00} modes created by walk-off of the UV by using relatively thin BBO crystals. At present, however, the lower bound on the BBO thickness is limited by the loss of conversion efficiency at high power.

  2. Photoelectron trapping in N2O 7σ-->kσ resonant ionization

    NASA Astrophysics Data System (ADS)

    Rathbone, G. J.; Poliakoff, E. D.; Bozek, John D.; Toffoli, Daniele; Lucchese, R. R.

    2005-07-01

    Vibrationally resolved photoelectron spectroscopy of the N2O+(AΣ+2) state is used to compare the dependence of the photoelectron dynamics on molecular geometry for two shape resonances in the same ionization channel. Spectra are acquired over the photon energy range of 18⩽hν⩽55eV. There are three single-channel resonances in this range, two in the 7σ→kσ channel and one in the 7σ→kπ channel. Vibrational branching ratio curves are determined by measuring vibrationally resolved photoelectron spectra as a function of photon energy, and theoretical branching ratio curves are generated via Schwinger variational scattering calculations. In the region 30⩽hν⩽40eV, there are two shape resonances (kσ and kπ). The kσ ionization resonance is clearly visible in vibrationally resolved measurements at hν =35eV, even though the total cross section in this channel is dwarfed by the cross section in the degenerate, more slowly varying 7σ→kπ channel. This kσ resonance is manifested in non-Franck-Condon behavior in the approximately antisymmetric ν3 stretching mode, but it is not visible in the branching ratio curve for the approximately symmetric ν1 stretch. The behavior of the 35-eV kσ resonance is compared to a previously studied N2O 7σ →kσ shape resonance at lower energy. The mode sensitivity of the 35-eV kσ resonance is the opposite of what was observed for the lower-energy resonance. The contrasting mode-specific behavior observed for the high- and low-energy 7σ →kσ resonances can be explained on the basis of the "approximate" symmetry of the quasibound photoelectron resonant wave function, and the contrasting behavior reflects differences in the continuum electron trapping. An examination of the geometry dependence of the photoelectron dipole matrix elements shows that the kσ resonances have qualitatively different dependences on the individual bond lengths. The low-energy resonance is influenced only by changes in the end-to-end length

  3. Resonance effects in two-photon double ionization of H2 by femtosecond XUV laser pulses

    NASA Astrophysics Data System (ADS)

    Guan, Xiaoxu; Bartschat, Klaus; Schneider, Barry I.; Koesterke, Lars

    2013-10-01

    We investigate the effect of the pulse length on the two-photon double ionization (DI) of H2 in the direct domain, for a femtosecond (fs) laser with a polarization vector oriented along the molecular axis. In the fixed-nuclei approximation, we find that the doubly excited Q11Σu+ states manifest themselves as resonances in the angle-integrated cross sections if the laser interaction lasts longer than about 3 fs. Decay into single-ionization channels does not significantly affect the shape of the angular distribution. A sharp rise in the probability for DI, due to virtual sequential ionization, occurs when the photon energy approaches the threshold for sequential DI.

  4. Resonance-Enhanced Multiphoton Ionization Mass Spectrometry (REMPI-MS): Applications for Process Analysis

    NASA Astrophysics Data System (ADS)

    Streibel, Thorsten; Zimmermann, Ralf

    2014-06-01

    Process analysis is an emerging discipline in analytical sciences that poses special requirements on analytical techniques, especially when conducted in an online manner. Mass spectrometric methods seem exceedingly suitable for this task, particularly if a soft ionization method is applied. Resonance-enhanced multiphoton ionization (REMPI) in combination with time-of-flight mass spectrometry (TOFMS) provides a selective and sensitive means for monitoring (poly)aromatic compounds in process flows. The properties of REMPI and various variations of the ionization process are presented. The potential of REMPI for process analysis is highlighted with several examples, and drawbacks of the method are also noted. Applications of REMPI-TOFMS for the detection and monitoring of aromatic species in a large variety of combustion processes comprising flames, vehicle exhaust, and incinerators are discussed. New trends in technical development and combination with other analytical methods are brought forward.

  5. Rydberg levels and ionization potential of francium measured by laser-resonance ionization in a hot cavity

    SciTech Connect

    Andreev, S.V.; Mishin, V.I.; Letokhov, V.S.

    1988-10-01

    A highly sensitive method of detecting atoms in samples has been used for spectral investigations of the rare radioactive element Fr. The method is based on laser-resonance photoionization of Fr atoms in a hot quasi-enclosed cavity. The investigations have been carried out with samples in which short-lived radioactive /sup 221/Fr atoms formed at a rate of approximately 10/sup 3/ atoms/sec. The data obtained, to our knowledge for the first time, on the energies of the high-lying Rydberg levels of the /sup 2/S/sub 1/2/ and /sup 2/D series have made it possible to determine the electron binding energy of the 7p /sup 2/P/sub 3/2/ state and to establish the ionization potential of Fr accurately.

  6. Determination of iodine in oyster tissue by isotope dilution laser resonance ionization mass spectrometry

    SciTech Connect

    Fassett, J.D.; Murphy, T.J. )

    1990-02-15

    The technique of laser resonance ionization mass spectrometry has been combined with isotope dilution analysis to determine iodine in oyster tissue. The long-lived radioisotope, 129I, was used to spike the samples. Samples were equilibrated with the 129I, wet ashed under controlled conditions, and iodine separated by coprecipitation with silver chloride. The analyte was dried as silver ammonium iodide upon a tantalum filament from which iodine was thermally desorbed in the resonance ionization mass spectrometry instrument. A single-color, two-photon resonant plus one-photon ionization scheme was used to form positive iodine ions. Long-lived iodine signals were achieved from 100 ng of iodine. The precision of 127I/129I measurement has been evaluated by replicate determinations of the spike, the spike calibration samples, and the oyster tissue samples and was 1.0%. Measurement precision among samples was 1.9% for the spike calibration and 1.4% for the oyster tissue. The concentration of iodine determined in SRM 1566a, Oyster Tissue, was 4.44 micrograms/g with an estimate of the overall uncertainty for the analysis of +/- 0.12 microgram/g.

  7. Hot-cavity studies for the Resonance Ionization Laser Ion Source

    NASA Astrophysics Data System (ADS)

    Henares, J. L.; Lecesne, N.; Hijazi, L.; Bastin, B.; Kron, T.; Lassen, J.; Le Blanc, F.; Leroy, R.; Osmond, B.; Raeder, S.; Schneider, F.; Wendt, K.

    2016-09-01

    The Resonance Ionization Laser Ion Source (RILIS) has emerged as an important technique in many Radioactive Ion Beam (RIB) facilities for its reliability, and ability to ionize target elements efficiently and element selectively. GISELE is an off-line RILIS test bench to study the implementation of an on-line laser ion source at the GANIL separator facility. The aim of this project is to determine the best technical solution which combines high selectivity and ionization efficiency with small ion beam emittance and stable long term operation. The ion source geometry was tested in several configurations in order to find a solution with optimal ionization efficiency and beam emittance. Furthermore, a low work function material was tested to reduce the contaminants and molecular sidebands generated inside the ion source. First results with ZrC ionizer tubes will be presented. Furthermore, a method to measure the energy distribution of the ion beam as a function of the time of flight will be discussed.

  8. Observation of orbiting resonances in He((3)S(1)) + NH3 Penning ionization.

    PubMed

    Jankunas, Justin; Jachymski, Krzysztof; Hapka, Michał; Osterwalder, Andreas

    2015-04-28

    Resonances are among the clearest quantum mechanical signatures of scattering processes. Previously, shape resonances and Feshbach resonances have been observed in inelastic and reactive collisions involving atoms or diatomic molecules. Structure in the integral cross section has been observed in a handful of elastic collisions involving polyatomic molecules. The present paper presents the observation of shape resonances in the reactive scattering of a polyatomic molecule, NH3. A merged-beam study of the gas phase He((3)S1) + NH3 Penning ionization reaction dynamics is described in the collision energy range 3.3 μeV < Ecoll < 10 meV. In this energy range, the reaction rate is governed by long-range attraction. Peaks in the integral cross section are observed at collision energies of 1.8 meV and 7.3 meV and are assigned to ℓ = 15,16 and ℓ = 20,21 partial wave resonances, respectively. The experimental results are well reproduced by theoretical calculations with the short-range reaction probability Psr = 0.035. No clear signature of the orbiting resonances is visible in the branching ratio between NH3 (+) and NH2 (+) formation.

  9. Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

    SciTech Connect

    J.A. Maloney, K.B. Beard, R.P. Johnson, A. Afanasev, S.A. Bogacz, Y.S. Derbenev, V.S. Morozov, B. Erdelyi

    2012-07-01

    A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

  10. Noble Gas Detection Using Resonance Ionization Spectroscopy and a Quadrupole Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Hurst, G. S.

    1983-10-01

    The technique of Resonance Ionization Spectroscopy (RIS) is being extended to develop a means for counting individual atoms of a selected isotope of a noble gas. In this method, lasers are used for RIS to obtain atomic species (Z) selectivity and a small quadrupole mass spectrometer provides isotopic (A) selectivity. A progress report on the objective of counting each atom of a particular isotope of a noble gas is given. Resonance ionization spectroscopy and its use for the detection of single atoms has been reviewed.' More recently, our efforts at ORNL have turned to the problem of direct counting of noble gas atoms2,3,4 as an alternative to decay counting of particular isotopes of noble gas species. For broader applications, the ORNL group is trying to develop a facility for counting a few rare gas atoms of a given isotopic variety in a sample. The detection of a small number of 81Kr atoms (<1000) is very important for groundwater dating, polar ice-cap dating, and nuclear waste disposal applications, and solar neutrino research. The ultimate goal is to count a small number (e.g., 100 to 1,000) of selected atoms having mass number A, even when mixed with 1012 or more atoms having mass number ± 1. The experimental schematic is shown in Figure 1. The concept for counting noble gas atoms with isotopic selectivity is to utilize a laser for ionizing atoms of a selected atomic

  11. Matrix-assisted ionization vacuum for high-resolution Fourier transform ion cyclotron resonance mass spectrometers.

    PubMed

    Wang, Beixi; Tisdale, Evgenia; Trimpin, Sarah; Wilkins, Charles L

    2014-07-15

    Matrix-assisted ionization vacuum (MAIV) produces charge states similar to electrospray ionization (ESI) from the solid state without requiring high voltage or added heat. MAIV differs from matrix-assisted laser desorption/ionization (MALDI) in that no laser is needed and abundant multiply charged ions are produced from molecules having multiple basic sites such as proteins. Here we introduce simple modifications to the commercial vacuum MALDI and ESI sources of a 9.4 T Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer to perform MAIV from both intermediate and atmospheric pressure. The multiply charged ions are shown for the proteins bovine insulin, ubiquitin, and lysozyme using 3-nitrobenzonitrile as matrix. These are the first examples of MAIV operating at pressures as low as 10(-6) mbar in an FT-ICR mass spectrometer source, and the expected mass resolving power of 100000 to 400000 is achieved. Identical protein charge states are observed with and without laser ablation indicating minimal, if any, role of photochemical ionization for the compounds studied.

  12. Isomer discrimination of polycyclic aromatic hydrocarbons in the Murchison meteorite by resonant ionization

    NASA Astrophysics Data System (ADS)

    Callahan, Michael P.; Abo-Riziq, Ali; Crews, Bridgit; Grace, Louis; de Vries, Mattanjah S.

    2008-12-01

    We have used two-color resonant two-photon ionization (2C-R2PI) mass spectrometry to discriminate between isomers of polycyclic aromatic hydrocarbons in the Murchison meteorite. We measured the 2C-R2PI spectra of chrysene and triphenylene seeded in a supersonic jet by laser desorption. Since each isomer differs in its R2PI spectrum, we can distinguish between isomers using wavelength dependent ionization and mass spectrometry. We found both chrysene and triphenylene in sublimates from carbonaceous residue obtained by acid demineralization of the Murchison meteorite. Their R2PI mass spectra show only the molecular ion, even though these samples contain a complex inventory of organic molecules.

  13. Zeptomole-sensitivity electrospray ionization--Fourier transform ion cyclotron resonance mass spectrometry of proteins.

    PubMed

    Belov, M E; Gorshkov, M V; Udseth, H R; Anderson, G A; Smith, R D

    2000-05-15

    Methods are being developed for ultrasensitive protein characterization based upon electrospray ionization (ESI) with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The sensitivity of a FTICR mass spectrometer equipped with an ESI source depends on the overall ion transmission, which combines the probability of ionization, transmission efficiency, and ion trapping in the FTICR cell. Our developments implemented in a 3.5 tesla FTICR mass spectrometer include introduction and optimization of a newly designed electrodynamic ion funnel in the ESI interface, improving the ion beam characteristics in a quadrupole-electrostatic ion guide interface, and modification of the electrostatic ion guide. These developments provide a detection limit of approximately 30 zmol (approximately 18,000 molecules) for proteins with molecular weights ranging from 8 to 20 kDa.

  14. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    PubMed

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium. PMID:11158669

  15. Detection of plutonium isotopes at lowest quantities using in-source resonance ionization mass spectrometry.

    PubMed

    Raeder, S; Hakimi, A; Stöbener, N; Trautmann, N; Wendt, K

    2012-11-01

    The in-source resonance ionization mass spectrometry technique was applied for quantification of ultratrace amounts of plutonium isotopes as a proof of principle study. In addition to an overall detection limit of 10(4) to 10(5) atoms, this method enables the unambiguous identification and individual quantification of the plutonium isotopes (238)Pu and (241)Pu which are of relevance for dating of radiogenic samples. Due to the element-selective ionization process, these isotopes can be measured even under a high surplus of isobaric contaminations from (238)U or (241)Am, which considerably simplifies chemical preparation. The technique was developed, tested, and characterized on a variety of synthetic and calibration samples and is presently applied to analyze environmental samples.

  16. Resonance Enhanced Multi-Photon Ionization (rempi) and Double Resonance Uv-Uv and Ir-Uv Spectroscopic Investigation Isocytosine

    NASA Astrophysics Data System (ADS)

    Lee, Seung Jun; Min, Ahreum; Ahn, Ahreum; Moon, Cheol Joo; Choi, Myong Yong; Ishiuchi, Shun-Ichi; Miyazaki, Mitsuhiko; Fujii, Masaaki

    2013-06-01

    Isocytosine(iC), 2-aminouracil, is a non-natural nucleobase and its functional group's positions resemble those of guanine; therefore, its spectroscopic investigation is worthy of attention especially for the natural/unnatural base pairs with guanine and isoguanine. In this study, resonance enhanced multi-photon ionization (REMPI) and UV/IR-UV double resonance spectra of iC in the gas phase are presented. The collaboration work between Tokyo Institute of Technology, Japan and Gyeongsang National University, Korea using laser ablation and thermal evaporation, respectively, for producing jet-cooled iC is presented and discussed. The REMPI spectrum of iC monomers is recorded in the spectral range of 35000 to 36400cm-1, showing very congested π-π* vibronic bands. UV-UV hole burning spectroscopy is further conducted to investigate the conformational landscapes of iC monomers. Moreover, the presence of free OH band from IR-UV double resonance spectroscopy in combination with quantum chemical calculations convinces that the iC monomer in free-jet expansion experiment is an enol tautomer. However, a possible presence of a keto tautomer of iC may be provided by employing a pico-second experiment on iC.

  17. Cosmological constraints in the presence of ionizing and resonance radiation at recombination

    SciTech Connect

    Bean, Rachel; Melchiorri, Alessandro; Silk, Joseph

    2007-03-15

    With the recent measurement of full sky cosmic microwave background (CMB) polarization from WMAP, key cosmological degeneracies have been broken, allowing tighter constraints to be placed on cosmological parameters inferred assuming a standard recombination scenario. Here we consider the effect on cosmological constraints if additional ionizing and resonance radiation sources are present at recombination. We find that the new CMB data significantly improve the constraints on the additional radiation sources, with log{sub 10}[{epsilon}{sub {alpha}}]<-0.5 and log{sub 10}[{epsilon}{sub i}]<-2.4 at 95% c.l. for resonance and ionizing sources, respectively. Including the generalized recombination scenario, however, we find that the constraints on the scalar spectral index n{sub s} are weakened to n{sub s}=0.98{+-}0.03, with the n{sub s}=1 case now well inside the 95% c.l. The relaxation of constraints on tensor modes, scale invariance, dark energy and neutrino masses are also discussed.

  18. Resonance-enhanced multiphoton ionization of CH₂Br₂: Rydberg states, photofragmentation, and CH spectra.

    PubMed

    Long, Jingming; Wang, Huasheng; Kvaran, Ágúst

    2014-03-13

    Mass-resolved (2 + n) resonance-enhanced multiphoton ionization (REMPI) spectra of CH2Br2 in the two-photon resonance excitation region from 71 200 to 82 300 cm(-1) were recorded and analyzed. Spectral structures allowed characterization of new molecular Rydberg states. C*((1)D2) was found to be an important intermediate in the photodissociation processes. A broad spectral feature peaking at about 80 663 cm(-1) in the C(+) spectrum and frequently seen in related studies is reinterpreted and associated with switching between three- and two-photon ionization of C*((1)D2). Analysis of band structures due to transitions from the A(2)Δ state of CH* that were seen in the CH(+) and C(+) REMPI spectra allowed characterization of three electronic states of CH, assigned as E(2)Π, D(2)Π, and F(2)Σ(+), which clarifies a long-term puzzle concerning the energetics of the CH radical. Predissociation of the E, D, and F states to form C*((1)D2) occurs. Bromine atomic lines were observed and are believed to be associated with bromine atom formation via predissociation of CH2Br2 Rydberg states.

  19. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    SciTech Connect

    Shneider, Mikhail N.; Miles, Richard B.

    2012-08-15

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  20. Spectroscopy and Ionization Thresholds of Isoelectronic 1-PHENYLALLYL and Benzylallenyl Resonance Stabilized Radicals

    NASA Astrophysics Data System (ADS)

    Sebree, Joshua A.; Kidwell, Nathan; Buchanan, Evan; Zwier, Timothy S.; Zgierski, Marek

    2011-06-01

    In recent years it has been proposed that resonance-stabilized radicals (RSRs) may play an important role as intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs). RSRs gain extra stability by delocalizing the unpaired electron through a neighboring conjugated π-system. Because of this extra stability, RSRs are able to build up in concentration, allowing for the creation of larger, more complex systems through their recombination with other RSRs. Mass-selective two-color resonant two-photon ionization spectra of two RSRs, phenylallyl and benzylallenyl radicals, have been recorded under jet-cooled conditions. These two radicals, while sharing the same radical conjugation, have unique properties. The phenylallyl and benzylallenyl radicals were respectively produced via discharge of trans-β-methylstyrene and benzylallene in argon prior to supersonic expansion. The D0-D1 origin of the phenylallyl radical was found at 19204 wn and was found to have a strong vertical ionization energy of 6.905(2) eV. By comparison, the benzylallenyl radical has an origin at 19703 wn and, while showing similar Franck-Condon activity to phenylallyl, has an IP curve indicative of a large geometry change between the ground state and the ion 7.50(2) eV. Visible-visible holeburning was used to show that each radical exists in one conformeric form in the expansion. The CH stretch region of each radical was taken using D0-Resonant Ion Dip Infrared Spectroscopy in a novel four laser experiment. A combination of this and DFT calculations was used to show that each radical exists in a trans geometry.

  1. Studies of 4-CHLORO-2-FLUOROANISOLE by Two-Color Resonant Two-Photon Mass-Analyzed Threshold Ionization Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Pei-Ying; Tzeng, Wen-Bih

    2016-06-01

    We applied the two-color resonant two-photon mass analyzed threshold ionization technique to record the cation spectra of 4-chloro-2-fluoroanisole by ionizing via five intermediate vibronic levels. The excitation and adiabatic ionization energies were determined to be 35 227, and 67 218 wn, respectively. Spectral analysis and theoretical calculation suggest that the geometry of the aromatic ring of the neutral species in the S1 state is non-planar, but that of the cation in the D0 state is planar.

  2. Resonant two-photon ionization electronic spectroscopy of the silver trimer

    NASA Astrophysics Data System (ADS)

    Cheng, P. Y.; Duncan, M. A.

    1989-10-01

    Silver metal clusters are produced by excimer lasers vaporization (308 nm) in a pulsed supersonic nozzle cluster source. The triatomic species is selectively ionized in a resonant two-photon absorption process via an excited electronic state with an origin at 26971±10 cm-1 (3.35 eV). Vibronic structure extending over 1500 cm-1 involves cleanly resolved bands at low energy merging to a quasi-continuum at higher energy. Vibronic analysis are considered for a triangular structure with or without Jahn-Teller interaction in the excited state. No simple analytic expression successfully fits the level structure. However, the spectrum is qualitatively consistent with a 2E` excited state with intermediate Jahn-Teller interaction.

  3. Autoionization Resonances in Orientation and Alignment Parameters for Excited Ions after Electron Impact Ionization.

    NASA Astrophysics Data System (ADS)

    Balashov, Vselovod; Bartschat, Klaus; Marchalant, Pascale

    1997-04-01

    We have extended previous work for alignment and orientation parameters in simultaneous ionization-excitation [1] to include the effect of autoionizing resonances. The expected effect is similar to that suggested for photoionization via autoionizing states [2]. Special emphasis is given to the process e + He --> e_scattered+e_ejected +He^+(2p), followed by He^+(2p) --> He^+(1s) + γ where the scattered electron and the emitted photon are detected in coincidence. 1. R. Schwienhorst, A. Raeker, K. Bartschat and K. Blum (1996), 1. J. Phys. B 29, 2305 2. V.V. Balashov, N.M. Kabachnik and V.S. Senashenko (1983), 2. Book of Abstracts ICPEAC XIII, 23 permanent address: Moscow State University

  4. High efficiency direct detection of ions from resonance ionization of sputtered atoms

    DOEpatents

    Gruen, D.M.; Pellin, M.J.; Young, C.E.

    1985-01-16

    A method and apparatus are provided for trace and other quantitative analysis with high efficiency of a component in a sample, with the analysis involving the removal by ion or other bombardment of a small quantity of ion and neutral atom groups from the sample, the conversion of selected neutral atom groups to photoions by laser initiated resonance ionization spectroscopy, the selective deflection of the photoions for separation from original ion group emanating from the sample, and the detection of the photoions as a measure of the quantity of the component. In some embodiments, the original ion group is accelerated prior to the RIS step for separation purposes. Noise and other interference are reduced by shielding the detector from primary and secondary ions and deflecting the photoions sufficiently to avoid the primary and secondary ions.

  5. High efficiency direct detection of ions from resonance ionization of sputtered atoms

    DOEpatents

    Gruen, Dieter M.; Pellin, Michael J.; Young, Charles E.

    1986-01-01

    A method and apparatus are provided for trace and other quantitative analysis with high efficiency of a component in a sample, with the analysis involving the removal by ion or other bombardment of a small quantity of ion and neutral atom groups from the sample, the conversion of selected neutral atom groups to photoions by laser initiated resonance ionization spectroscopy, the selective deflection of the photoions for separation from original ion group emanating from the sample, and the detection of the photoions as a measure of the quantity of the component. In some embodiments, the original ion group is accelerated prior to the RIS step for separation purposes. Noise and other interference are reduced by shielding the detector from primary and secondary ions and deflecting the photoions sufficiently to avoid the primary and secondary ions.

  6. Molecular beam resonant two-photon ionization study of caffeine and its hydrated clusters

    NASA Astrophysics Data System (ADS)

    Kim, Doory; Kim, Hyung Min; Yang, Key Young; Kim, Seong Keun; Kim, Nam Joon

    2008-04-01

    We investigated electronically excited states of caffeine and its 1:1 complex with water by using resonant two-photon ionization (R2PI) and UV-UV hole-burning techniques. Strong vibronic coupling between a pair of close-lying π-π * and n-π * transitions is proposed to be responsible for the broad spectral feature observed. By comparing the experimental results with those of theoretical calculations, both the O-bonded and N-bonded forms were suggested to be initially produced for the 1:1 complex. The electronic transitions of the O-bonded complex were blueshifted in the R2PI spectrum. For the N-bonded complex, the excited state undergoes an ultrafast decay process, followed by dissociation on a repulsive potential energy surface, which gives rise to a characteristically anomalous cluster distribution in nanosecond experiments.

  7. Resonant two-photon ionization spectroscopy of Al atoms and dimers solvated in helium nanodroplets

    SciTech Connect

    Krasnokutski, Serge A.; Huisken, Friedrich

    2015-02-28

    Resonant two-photon ionization (R2PI) spectroscopy has been applied to investigate the solvation of Al atoms in helium droplets. The R2PI spectra reveal vibrational progressions that can be attributed to Al–He{sub n} vibrations. It is found that small helium droplets have very little chance to pick up an aluminum atom after collision. However, the pick-up probability increases with the size of the helium droplets. The absorption band that is measured by monitoring the ions on the mass of the Al dimer is found to be very little shifted with respect to the Al monomer band (∼400 cm{sup −1}). However, using the same laser wavelength, we were unable to detect any Al{sub n} photoion with n larger than two.

  8. Resonant two-photon ionization spectroscopy of jet-cooled NiPt

    NASA Astrophysics Data System (ADS)

    Taylor, Scott; Spain, Eileen M.; Morse, Michael D.

    1990-03-01

    Resonant two-photon ionization spectroscopy of jet-cooled NiPt has been used to investigate the possibility of d-electron contributions to the bonding in this species. Based on an abrupt onset of predissociation, the bond strength of NiPt is assigned as D0(NiPt)=2.798±0.003 eV. Comparisons of scans using ArF (6.42 eV) or F2 (7.87 eV) radiation as the ionization laser yield IP(NiPt)=8.02±0.15 eV, from which we derive D0(Ni+-Pt)=2.41±0.15 eV and D0(Ni-Pt+) =3.58±0.35 eV. High resolution studies of the 6-0 and 8-0 bands of one of the three identifiable progressions demonstrate an Ω'=0←Ω`=0 transition with r'e =2.3396±0.0039Å and r″0 =2.2078±0.0023Å. The short bond length and large bond strength of NiPt, as compared to the corresponding values (re=2.330±0.003Å and D0=2.34±0.10 eV) for the coinage metal analog, CuAu, demonstrate significant d-orbital contributions to the bonding in NiPt.

  9. Developments for resonance ionization laser spectroscopy of the heaviest elements at SHIP

    NASA Astrophysics Data System (ADS)

    Lautenschläger, F.; Chhetri, P.; Ackermann, D.; Backe, H.; Block, M.; Cheal, B.; Clark, A.; Droese, C.; Ferrer, R.; Giacoppo, F.; Götz, S.; Heßberger, F. P.; Kaleja, O.; Khuyagbaatar, J.; Kunz, P.; Mistry, A. K.; Laatiaoui, M.; Lauth, W.; Raeder, S.; Walther, Th.; Wraith, C.

    2016-09-01

    The experimental determination of atomic levels and the first ionization potential of the heaviest elements (Z ⩾ 100) is key to challenge theoretical predictions and to reveal changes in the atomic shell structure. These elements are only artificially produced in complete-fusion evaporation reactions at on-line facilities such as the GSI in Darmstadt at a rate of, at most, a few atoms per second. Hence, highly sensitive spectroscopic methods are required. Laser spectroscopy is one of the most powerful and valuable tools to investigate atomic properties. In combination with a buffer-gas filled stopping cell, the Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique provides the highest sensitivity for laser spectroscopy on the heaviest elements. The RADRIS setup, as well as the measurement procedure, have been optimized and characterized using the α -emitter 155 Yb in on-line conditions, resulting in an overall efficiency well above 1%. This paves the way for a successful search of excited atomic levels in nobelium and heavier elements.

  10. Resonantly Enhanced Betatron Hard X-rays from Ionization Injected Electrons in a Laser Plasma Accelerator.

    PubMed

    Huang, K; Li, Y F; Li, D Z; Chen, L M; Tao, M Z; Ma, Y; Zhao, J R; Li, M H; Chen, M; Mirzaie, M; Hafz, N; Sokollik, T; Sheng, Z M; Zhang, J

    2016-06-08

    Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 10(8)/shot and 10(8 )photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3(rd) generation synchrotrons.

  11. Resonantly Enhanced Betatron Hard X-rays from Ionization Injected Electrons in a Laser Plasma Accelerator

    PubMed Central

    Huang, K.; Li, Y. F.; Li, D. Z.; Chen, L. M.; Tao, M. Z.; Ma, Y.; Zhao, J. R.; Li, M. H.; Chen, M.; Mirzaie, M.; Hafz, N.; Sokollik, T.; Sheng, Z. M.; Zhang, J.

    2016-01-01

    Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 108/shot and 108 photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3rd generation synchrotrons. PMID:27273170

  12. Analysis of /sup 81/Kr in groundwater using laser resonance ionization spectroscopy

    SciTech Connect

    Kramer, S.D.; Hurst, G.S.; Chen, C.H.; Payne, M.G.; Allman, S.L.; Phillips, R.C.; Lehmann, B.E.; Oeschger, H.; Loosli, H.H.; Willis, R.D.

    1985-10-01

    A new analytical technique based on resonant ionization of krypton with a vacuum ultraviolet (VUV) laser source was used to determine low-level /sup 81/Kr concentrations in groundwater. The long half-life (210,000 years) and low concentration (1.3 x 10/sup 3/ /sup 81/Kr atoms per liter of modern water at 10/sup 0/C) make the detection of /sup 81/Kr by radioactive counting techniques extremely difficult. In this method, krypton gas was removed from water taken from an underground Swiss aquifer using standard cryogenic and chromatographic techniques. Stable krypton isotopes were then reduced by a factor of 10/sup 7/ by a two-stage isotopic enrichment cycle using a commercially available mass spectrometer. The enriched gas containing about 10/sup 8/ stable krypton atoms and about 10/sup 3/ atoms of /sup 81/Kr was implanted into a silicon disc. This disc was then placed in the high vacuum final counting chamber and the krypton was released by laser annealing. This chamber contained a quadrupole mass spectrometer which used a pulsed VUV laser source as the ionizer. The measured signal indicated that the sample contained 1200 (+-300) atoms of /sup 81/Kr.

  13. (2+1) resonance-enhanced multiphoton ionization-photoelectron spectroscopy of the OH radical

    NASA Astrophysics Data System (ADS)

    de Beer, Esther; Koopmans, M. P.; de Lange, C. A.; Wang, Yumin; Chupka, W. A.

    1991-06-01

    A (2+1) resonance-enhanced multiphoton ionization-photoelectron spectroscopy (REMPIPES) study of the OH radical is carried out in the two-photon energy region between 81,300 and 88,900/cm, using a frequency-doubled excimer-pumped dye laser with a pulse width of about 10 ns at a repetition rate of 30 Hz. The laser output was focused into the ionization region of a 'magnetic bottle' spectrometer. The known D 2Sigma(-) (v-prime = 0-2) and the hitherto unobserved 3 2Sigma(-) (v-prime = 0) intermediate states in this region are shown to possess a predominant Rydberg character. Spectrum physical parameters are derived for these states from the rotational structure in the REMPI spectrum. The observed new state is demonstrated to be in excellent agreement with a previous calculation. Theory also predicts that the repulsive 2 2Pi state diabatically crosses the potential curves of the ns-sigma and np-sigma Rydberg states, with the effect that significant heterogeneous predissociation might be expected.

  14. Resonantly Enhanced Betatron Hard X-rays from Ionization Injected Electrons in a Laser Plasma Accelerator.

    PubMed

    Huang, K; Li, Y F; Li, D Z; Chen, L M; Tao, M Z; Ma, Y; Zhao, J R; Li, M H; Chen, M; Mirzaie, M; Hafz, N; Sokollik, T; Sheng, Z M; Zhang, J

    2016-01-01

    Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 10(8)/shot and 10(8 )photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3(rd) generation synchrotrons. PMID:27273170

  15. Resonantly Enhanced Betatron Hard X-rays from Ionization Injected Electrons in a Laser Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Huang, K.; Li, Y. F.; Li, D. Z.; Chen, L. M.; Tao, M. Z.; Ma, Y.; Zhao, J. R.; Li, M. H.; Chen, M.; Mirzaie, M.; Hafz, N.; Sokollik, T.; Sheng, Z. M.; Zhang, J.

    2016-06-01

    Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission via ionization injection from the K-shell electrons of nitrogen into the accelerating bucket. A total photon yield of 8 × 108/shot and 108 photons with energy greater than 110 keV is obtained. The yield is 10 times higher than that achieved with self-injection mode in helium under similar laser parameters. The simulation suggests that ionization-injected electrons are quickly accelerated to the driving laser region and are subsequently driven into betatron resonance. The present scheme enables the single-stage betatron radiation from LWFA to be extended to bright γ-ray radiation, which is beyond the capability of 3rd generation synchrotrons.

  16. Impurity characterization of solar wind collectors for the genesis discovery mission by resonance ionization mass spectrometry.

    SciTech Connect

    Calaway, W. F.

    1999-02-01

    NASA's Genesis Discovery Mission is designed to collect solar matter and return it to earth for analysis. The mission consists of launching a spacecraft that carries high purity collector materials, inserting the spacecraft into a halo orbit about the L1 sun-earth libration point, exposing the collectors to the solar wind for two years, and then returning the collectors to earth. The collectors will then be made available for analysis by various methods to determine the elemental and isotopic abundance of the solar wind. In preparation for this mission, potential collector materials are being characterized to determine baseline impurity levels and to assess detection limits for various analysis techniques. As part of the effort, potential solar wind collector materials have been analyzed using resonance ionization mass spectrometry (RIMS). RIMS is a particularly sensitivity variation of secondary neutral mass spectrometry that employs resonantly enhanced multiphoton ionization (REMPI) to selectively postionize an element of interest, and thus discriminates between low levels of that element and the bulk material. The high sensitivity and selectivity of RIMS allow detection of very low concentrations while consuming only small amounts of sample. Thus, RIMS is well suited for detection of many heavy elements in the solar wind, since metals heavier than Fe are expected to range in concentrations from 1 ppm to 0.2 ppt. In addition, RIMS will be able to determine concentration profiles as a function of depth for these implanted solar wind elements effectively separating them from terrestrial contaminants. RIMS analyses to determine Ti concentrations in Si and Ge samples have been measured. Results indicate that the detection limit for RIMS analysis of Ti is below 100 ppt for 10{sup 6} averages. Background analyses of the mass spectra indicate that detection limits for heavier elements will be similar. Furthermore, detection limits near 1 ppt are possible with higher

  17. Competition between two-photon-resonant three-photon ionization and four-wave mixing in Xe

    SciTech Connect

    Nagai, Hidekazu; Nakanaga, Taisuke

    2011-12-15

    Competitive inhibition of a resonance enhanced multiphoton ionization process by a resonant four-wave mixing has been observed in Xe atoms. When an intense IR (1064 nm) laser was applied to a sample of Xe which was also being irradiated by a UV laser tuned to the two-photon absorption line of Xe, the two-photon-resonant three-photon ionization signals decreased with increasing IR laser power. This phenomenon is dependent on the resonant states of Xe and the polarization of the two laser beams. Three 6s excited states [5/2]{sub 2}, [3/2]{sub 2}, and [1/2]{sub 0} were examined. At the [1/2]{sub 0} resonant state, the ion signals were not decreased but slightly increased with the increase of the IR laser power. No suppression of the ion signal was observed at the [5/2]{sub 2} resonant state, when the polarization directions of the lasers were perpendicular to each other. The result of the polarization dependence reflects the selection rules of four-wave mixing. A simple rate equation analysis including the contribution of two-photon ionization from the [1/2]{sub 0} state by the IR laser well represents the IR laser-power dependence of the ion signal.

  18. Verification Results of Jet Resonance-enhanced Multiphoton Ionization as a Real-time PCDD/F Emission Monitor

    EPA Science Inventory

    The Jet REMPI (Resonance Enhanced Multiphoton Ionization) monitor was tested on a hazardous waste firing boiler for its ability to determine concentrations of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/Fs). Jet REMPI is a real time instrument capable of highly selec...

  19. Nonadiabatic dynamics and multiphoton resonances in strong-field molecular ionization with few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Tagliamonti, Vincent; Sándor, Péter; Zhao, Arthur; Rozgonyi, Tamás; Marquetand, Philipp; Weinacht, Thomas

    2016-05-01

    We study strong-field molecular ionization using few- (four to ten) cycle laser pulses. Employing a supercontinuum light source, we are able to tune the optical laser wavelength (photon energy) over a range of ˜200 nm (500 meV). We measure the photoelectron spectrum for a series of different molecules as a function of laser intensity, frequency, and bandwidth and illustrate how the ionization dynamics vary with these parameters. We find that multiphoton resonances and nonadiabatic dynamics (internal conversion) play an important role and result in ionization to different ionic continua. Interestingly, while nuclear dynamics can be "frozen" for sufficiently short laser pulses, we find that resonances strongly influence the photoelectron spectrum and final cationic state of the molecule regardless of pulse duration—even for pulses that are less than four cycles in duration.

  20. Electronic dynamics of charge resonance enhanced ionization probed by laser-induced alignment in C2H2

    NASA Astrophysics Data System (ADS)

    Cornaggia, C.

    2016-10-01

    Although charge resonance enhanced ionization (CREI) be an ubiquitous effect in molecules in strong laser fields, the associated electron emission remains difficult to deal with. The main reason relies on the fact that CREI is part of an overall multielectron ionization, where the initial steps of single and dissociative ionization of neutral species dominate the electron spectrum. Using the rescattered electrons, we show that it is possible to address the electron signal from CREI without any contribution from other electron signals. The electrons from CREI are preferentially emitted when the molecular axis is parallel to the laser electric field as expected from its electronic dynamics. Acetylene is chosen for demonstration purpose because single ionization, which is not related to CREI, is more pronounced when the C2H2 molecular axis is perpendicular to the laser electric field.

  1. Pulse train dependence of electron dynamics during resonant femtosecond laser nonlinear ionization of a Na4 cluster

    NASA Astrophysics Data System (ADS)

    Zhao, Xinyu; Wang, Cong; Luo, Zhi; Yin, Kai; Dong, Xinran; Song, Yuxin; Duan, Ji'an

    2016-11-01

    In this study, a real-time and real-space time-dependent density functional theory (TDDFT) is applied to describe nonlinear electron-photon interactions during a resonant femtosecond laser pulse train photoionization of a Na4 cluster. The effects of key pulse train parameters, such as the spatial/temporal pulse energy distribution, pulse number per train, pulse separation and pulse phase on resonant absorption, are discussed. The calculations show that the resonant effect and the nonlinear electron dynamics, including energy absorption, electron emission, dipole response and ionization probability, can be controlled by shaping the ultrafast laser pulse train.

  2. Low-frequency resonances of the refractive index in weakly ionized plasma with an admixture of dust

    SciTech Connect

    Prudskikh, V. V.

    2013-12-15

    The propagation of low-frequency electromagnetic waves along the magnetic field in weakly ionized plasma with an admixture of dust is studied in the framework of the Hall magnetohydrodynamics. Explicit expressions for the coefficients of magnetic field diffusion in plasma are derived. The resonance of the refractive index is found to occur for either right- or left-hand polarized waves. A quantitative criterion is obtained that allows one to determine the polarization of waves that experience resonance at given plasma parameters. The physical mechanism of the resonance is discussed, and the obtained results are compared with the available literature data.

  3. Attosecond pulse formation via switching of resonant interaction by tunnel ionization

    NASA Astrophysics Data System (ADS)

    Antonov, V. A.; Akhmedzhanov, T. R.; Radeonychev, Y. V.; Kocharovskaya, Olga

    2015-02-01

    We derive an analytical solution uncovering the origin of few-cycle attosecond pulse formation from vacuum-ultraviolet (VUV) radiation in an atomic gas simultaneously irradiated by a moderately strong infrared (IR) laser field, which does not perturb atoms in the ground state, but induces rapid quasistatic ionization from the excited states [Polovinkin et al., Opt. Lett. 36, 2296 (2011), 10.1364/OL.36.002296]. The derived solution shows that the pulses are produced due to periodic switching of the resonant interaction between the incident VUV radiation and the atoms: turning it off near the crests of the IR-field strength and switching it back on near the IR-field zero crossings. We extend the method originally proposed by Polovinkin et al. [Opt. Lett. 36, 2296 (2011), 10.1364/OL.36.002296] to non-hydrogen-like media and show that the pulses can be produced from resonant VUV radiation in a variety of atomic gases. The pulses are nearly bandwidth limited without external adjustment of phases of the generated sidebands. Proximity of the carrier frequency of the produced pulses to intra-atomic resonances may allow their efficient utilization for nondestructive steering of ultrafast dynamics of the bound electrons. The experimental possibilities for attosecond pulse formation from 58.4 nm VUV radiation in helium and from 73.6 nm VUV radiation in neon dressed by the 3.9 μm laser field, as well as from 122 nm VUV radiation in atomic hydrogen dressed by C O2 -laser field are discussed.

  4. Photoionization Dynamics and Ion State Distributions in Single-Photon and Resonance-Enhanced Multiphoton Ionization of Molecules.

    NASA Astrophysics Data System (ADS)

    Braunstein, Matthew

    This thesis presents results of theoretical studies of single-photon ionization and resonance enhanced multiphoton ionization (REMPI) of several small molecules. The first part of the thesis examines shape resonances in the photoionization of O_2. Studies reported here include investigations of branching ratios of electronic multiplet states in the 3sigma _{g} and 1pi_ {u} photoionization of O_2 and a comparison of photoionization of the singlet states, a ^1Delta_{g} and d ^1prod_{g } (3ssigma_{g} 1pi_{g}), with that of the ground state of O_2. These studies show that the electronic exchange interaction between the ion core and the photoelectron in shape resonant energy regions profoundly affects the electronic state distributions of the molecular ion. We also report vibrational branching ratios in the single-photon ionization of O_2 , and in REMPI of O_2 via the G^3prod_{g} Rydberg state. In these studies, we find that a shape resonance causes a dependence of the electronic transition moment on the molecular geometry leading to non-Franck -Condon ion vibrational distributions and a dependence of the rotational branch intensity on the ion vibrational state. The second part of this thesis examines shape resonances in other molecules, focusing on the more general aspects of the photoionization dynamics. Here we present studies of the vibrational state distributions in the 7 sigma photoionization of the polyatomic N_2O, where a shape resonance causes non-Franck-Condon vibrational state distributions, the degree of which depends on the nuclear displacements involved and whether the shape resonance is localized on a particular bond. We also study the photoionization dynamics of the valence shell of Cl_2, where a shape resonance is also seen. Finally, we present studies of the K-shell ionization of CO. Studies in this energy region have assumed a new importance with the development of tunable X-ray synchrotron sources. Here, electronic relaxation in the production of a K

  5. Resonantly enhanced multiphoton ionization and zero kinetic energy photoelectron spectroscopy of chrysene: a comparison with tetracene.

    PubMed

    Zhang, Jie; Harthcock, Colin; Kong, Wei

    2012-07-01

    We report the electronic and vibrational spectroscopy of chrysene using resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. As an isomer of tetracene, chrysene contains a kink in the middle of the four fused hexagonal rings, which complicates not just the symmetry but, more importantly, the molecular orbitals and hence vibronic transitions. Incidentally, the two nearby electronically excited states of chrysene have the same symmetry, and vibronic coupling introduces no out-of-plane vibrational modes. As a result, the REMPI spectrum of chrysene contains essentially only in-plane ring deformation modes, similar to that of tetracene. However, density functional calculations using gaussian even after the inclusion of vibronic coupling can only duplicate the observed REMPI spectrum in a qualitative sense, and the agreement is considerably worse than our recent work on a few pericondensed polycyclic aromatic hydrocarbons and on tetracene. The ZEKE spectrum of chrysene via the origin band of the intermediate electronic state S(1), however, can be qualitatively reproduced by a straightforward Franck-Condon calculation. The ZEKE spectra from vibrationally excited states of the S(1), on the other hand, demonstrate some degree of mode selectivity: the overall intensity of the ZEKE spectrum can vary by an order of magnitude depending on the vibrational mode of the intermediate state. A scaling factor in the theoretical vibrational frequency for the cation is also needed to compare with the experimental result, unlike tetracene and pentacene.

  6. Spatially resolved measurement of singlet delta oxygen by radar resonance-enhanced multiphoton ionization.

    PubMed

    Wu, Yue; Zhang, Zhili; Ombrello, Timothy M

    2013-07-01

    Coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization (REMPI) was demonstrated to directly and nonintrusively measure singlet delta oxygen, O(2)(a(1)Δ(g)), with high spatial resolution. Two different approaches, photodissociation of ozone and microwave discharge plasma in an argon and oxygen flow, were utilized for O(2)(a(1)Δ(g)) generation. The d(1)Π(g)←a(1)Δ(g) (3-0) and d(1)Π(g)←a(1)Δ(g) (1-0) bands of O(2)(a(1)Δ(g)) were detected by Radar REMPI for two different flow conditions. Quantitative absorption measurements using sensitive off-axis integrated cavity output spectroscopy (ICOS) was used simultaneously to evaluate the accuracy and sensitivity of the Radar REMPI technique. The detection limit of Radar REMPI was found to be comparable to the ICOS technique with a detection threshold of approximately 10(14) molecules/cm(3) but with a spatial resolution that was 8 orders of magnitude smaller than the ICOS technique.

  7. Controlled-Resonant Surface Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

    SciTech Connect

    Lorenz, Matthias; Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2014-01-01

    This paper reports on the advancement of a controlled-resonance surface tapping-mode single capillary liquid junction extraction/ESI emitter for mass spectrometry imaging. The basic instrumental setup and the general operation of the system were discussed and optimized performance metrics were presented. The ability to spot sample, lane scan and chemically image in an automated and controlled fashion were demonstrated. Rapid, automated spot sampling was demonstrated for a variety of compound types including the cationic dye basic blue 7, the oligosaccharide cellopentaose, and the protein equine heart cytochrome c. The system was used for lane scanning and chemical imaging of the cationic dye crystal violet in inked lines on glass and for lipid distributions in mouse brain thin tissue sections. Imaging of the lipids in mouse brain tissue under optimized conditions provided a spatial resolution of approximately 35 m based on the ability to distinguish between features observed both in the optical and mass spectral chemical images. The sampling spatial resolution of this system was comparable to the best resolution that has been reported for other types of atmospheric pressure liquid extraction-based surface sampling/ionization techniques used for mass spectrometry imaging.

  8. Resonant two-photon ionization spectroscopy of jet-cooled UN: Determination of the ground state

    NASA Astrophysics Data System (ADS)

    Matthew, Daniel J.; Morse, Michael D.

    2013-05-01

    The optical transitions of supersonically cooled uranium nitride (UN) have been investigated in the range from 19 200 to 23 900 cm-1 using resonant two-photon ionization spectroscopy. A large number of bands have been observed, of which seven have been rotationally resolved and analyzed. All are found to arise from the same state, which is presumably the ground state of the molecule. From the analysis of the bands, the ground state has Ω = 3.5, with a bond length of 1.7650(12) Å. Comparisons to the known isovalent molecules are made, and the variations in ground state configuration are explained in terms of the configurational reordering that occurs with changes in the nuclear and ligand charges. It is concluded that the UN molecule is best considered as a U3+N3- species in which the closed shell nitride ligand interacts with a U3+ ion. The ground state of the molecule derives from a U3+ ion in its 7s15f 2 atomic configuration.

  9. Use of a Continuous Wave Laser and Pockels Cell for Sensitive High-Resolution Collinear Resonance Ionization Spectroscopy

    NASA Astrophysics Data System (ADS)

    de Groote, R. P.; Budinčević, I.; Billowes, J.; Bissell, M. L.; Cocolios, T. E.; Farooq-Smith, G. J.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Li, R.; Lynch, K. M.; Marsh, B. A.; Neyens, G.; Rossel, R. E.; Rothe, S.; Stroke, H. H.; Wendt, K. D. A.; Wilkins, S. G.; Yang, X.

    2015-09-01

    New technical developments have led to a 2 orders of magnitude improvement of the resolution of the collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing the high efficiency of the CRIS technique. Experimental linewidths of 20(1) MHz were obtained on radioactive beams of francium, allowing us for the first time to determine the electric quadrupole moment of the short lived [t1 /2=22.0 (5 ) ms ] 219Fr Qs=-1.21 (2 ) eb , which would not have been possible without the advantages offered by the new method. This method relies on a continuous-wave laser and an external Pockels cell to produce narrow-band light pulses, required to reach the high resolution in two-step resonance ionization. Exotic nuclei produced at rates of a few hundred ions/s can now be studied with high resolution, allowing detailed studies of the anchor points for nuclear theories.

  10. Use of a Continuous Wave Laser and Pockels Cell for Sensitive High-Resolution Collinear Resonance Ionization Spectroscopy.

    PubMed

    de Groote, R P; Budinčević, I; Billowes, J; Bissell, M L; Cocolios, T E; Farooq-Smith, G J; Fedosseev, V N; Flanagan, K T; Franchoo, S; Garcia Ruiz, R F; Heylen, H; Li, R; Lynch, K M; Marsh, B A; Neyens, G; Rossel, R E; Rothe, S; Stroke, H H; Wendt, K D A; Wilkins, S G; Yang, X

    2015-09-25

    New technical developments have led to a 2 orders of magnitude improvement of the resolution of the collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing the high efficiency of the CRIS technique. Experimental linewidths of 20(1) MHz were obtained on radioactive beams of francium, allowing us for the first time to determine the electric quadrupole moment of the short lived [t_{1/2}=22.0(5) ms] ^{219}Fr Q_{s}=-1.21(2) eb, which would not have been possible without the advantages offered by the new method. This method relies on a continuous-wave laser and an external Pockels cell to produce narrow-band light pulses, required to reach the high resolution in two-step resonance ionization. Exotic nuclei produced at rates of a few hundred ions/s can now be studied with high resolution, allowing detailed studies of the anchor points for nuclear theories. PMID:26451548

  11. A proposal for a novel H ion source based on electron cyclotron resonance heating and surface ionization

    SciTech Connect

    Tarvainen, Ollie A; Kurennoy, Sergey

    2008-01-01

    A design for a novel H{sup -} ion source based on electron cyclotron resonance plasma heating and surface ionization is presented. The plasma chamber of the source is an rf-cavity designed for TE{sub 111} eigenmode at 2.45 GHz. The desired mode is excited with a loop antenna. The ionization process takes place on a cesiated surface of a biased converter electrode. The H{sup -} ion beam is further 'self-extracted' through the plasma region. The magnetic field of the source is optimized for plasma generation by electron cyclotron resonance heating, and beam extraction. The design features of the source are discussed in detail and the attainable H{sup -} ion current, beam emittance and duty factor of the novel source are estimated.

  12. A Proposal for a Novel H- Ion Source Based on Electron Cyclotron Resonance Plasma Heating and Surface Ionization

    NASA Astrophysics Data System (ADS)

    Tarvainen, O.; Kurennoy, S.

    2009-03-01

    A design for a novel H- ion source based on electron cyclotron resonance plasma heating and surface ionization is presented. The plasma chamber of the source is an rf-cavity designed for TE111 eigenmode at 2.45 GHz. The desired mode is excited with a loop antenna. The ionization process takes place on a cesiated surface of a biased converter electrode. The H- ion beam is further "self-extracted" through the plasma region. The magnetic field of the source is optimized for plasma generation by electron cyclotron resonance heating, and beam extraction. The design features of the source are discussed in detail and the attainable H- ion current, beam emittance and duty factor of the novel source are estimated.

  13. Photofragmentation, state interaction, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization of HI

    SciTech Connect

    Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst

    2014-06-28

    Mass resolved resonance enhanced multiphoton ionization data for hydrogen iodide (HI), for two-photon resonance excitation to Rydberg and ion-pair states in the 69 600–72 400 cm{sup −1} region were recorded and analyzed. Spectral perturbations due to homogeneous and heterogeneous interactions between Rydberg and ion-pair states, showing as deformations in line-positions, line-intensities, and line-widths, were focused on. Parameters relevant to photodissociation processes, state interaction strengths and spectroscopic parameters for deperturbed states were derived. Overall interaction and dynamical schemes to describe the observations are proposed.

  14. Upgrade of the Resonance Ionization Mass Spectrometer for Precise Identification of Failed Fuel in a Fast Reactor

    SciTech Connect

    Iwata, Yoshihiro; Ito, Chikara; Harano, Hideki; Aoyama, Takafumi

    2011-12-13

    Isotopic analysis of krypton (Kr) and xenon (Xe) by resonance ionization mass spectrometry (RIMS) is an effective tool for identification of failed fuel in fast reactors to achieve their safety operation and high plant availability. Reliability of the failed fuel detection and location (FFDL) system depends on the precise determination of {sup 78}Kr/{sup 80}Kr, {sup 82}Kr/{sup 80}Kr and {sup 126}Xe/{sup 129}Xe isotopic ratios, which is mainly hampered by statistical errors for detection of the corresponding isotopes except {sup 82}Kr generated in large amounts during operation of fast reactors. In this paper, we report on improvements of the laser optical system of our spectrometer to increase the resonance ionization efficiency of Kr and Xe atoms, focusing on (i) utilization of the uniform YAG laser beam to improve the wavelength conversion efficiency of sum frequency generation and (ii) reflection of the ultraviolet light by a concave mirror to increase the photon density. The results indicate that our upgraded resonance ionization mass spectrometer has enough performance for isotopic analysis of Kr and Xe required in the Monju FFDL system.

  15. Automated ambient desorption-ionization platform for surface imaging integrated with a commercial Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Pól, Jaroslav; Vidová, Veronika; Kruppa, Gary; Kobliha, Václav; Novák, Petr; Lemr, Karel; Kotiaho, Tapio; Kostiainen, Risto; Havlícek, Vladimír; Volný, Michael

    2009-10-15

    A fully automated atmospheric pressure ionization platform has been built and coupled with a commercial high-resolution Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) instrument. The outstanding performance of this instrument allowed screening on the basis of exact masses in imaging mode. The main novel aspect was in the integration of the atmospheric pressure ionization imaging into the current software for matrix-assisted laser desorption ionization (MALDI) imaging, which allows the user of this commercial dual-source mass spectrometer to perform MALDI-MS and different ambient MS imaging from the same user interface and to utilize the same software tools. Desorption electrospray ionization (DESI) and desorption atmospheric pressure photoionization (DAPPI) were chosen to test the ambient surface imaging capabilities of this new ionization platform. Results of DESI imaging experiments performed on brain tissue sections are in agreement with previous MS imaging reports obtained by DESI imaging, but due to the high resolution and mass accuracy of the FTICR instrument it was possible to resolve several ions at the same nominal mass in the DESI-MS spectra of brain tissue. These isobaric interferences at low resolution are due to the overlap of ions from different lipid classes with different biological relevance. It was demonstrated that with the use of high-resolution MS fast imaging screening of lipids can be achieved without any preseparation steps. DAPPI, which is a relatively new and less developed ambient ionization technique compared to DESI, was used in imaging mode for the first time ever. It showed promise in imaging of phytocompounds from plant leaves, and selective ionization of a sterol lipid was achieved by DAPPI from a brain tissue sample.

  16. Double-electron above-threshold ionization resonances as interference phenomena

    NASA Astrophysics Data System (ADS)

    Armstrong, G. S. J.; Parker, J. S.; Taylor, K. T.

    2011-01-01

    We report calculations of double-ionization energy spectra and momentum distributions of laser-driven helium due to few-cycle pulses of wavelength 195 nm. The results are obtained from full-dimensional numerical integration of the two-electron time-dependent Schrödinger equation. A momentum-space analysis of doubly ionizing wavepackets shows that the concentric-ring structure of above-threshold double ionization, together with the associated structure of peaks in the total kinetic energy spectrum, may be attributed to wavepacket interference effects, where at least two doubly ionizing wavepackets from different recollision events populate the same spatial hemisphere.

  17. Observation of orbiting resonances in He({sup 3}S{sub 1}) + NH{sub 3} Penning ionization

    SciTech Connect

    Jankunas, Justin; Osterwalder, Andreas; Jachymski, Krzysztof; Hapka, Michał

    2015-04-28

    Resonances are among the clearest quantum mechanical signatures of scattering processes. Previously, shape resonances and Feshbach resonances have been observed in inelastic and reactive collisions involving atoms or diatomic molecules. Structure in the integral cross section has been observed in a handful of elastic collisions involving polyatomic molecules. The present paper presents the observation of shape resonances in the reactive scattering of a polyatomic molecule, NH{sub 3}. A merged-beam study of the gas phase He({sup 3}S{sub 1}) + NH{sub 3} Penning ionization reaction dynamics is described in the collision energy range 3.3 μeV < E{sub coll} < 10 meV. In this energy range, the reaction rate is governed by long-range attraction. Peaks in the integral cross section are observed at collision energies of 1.8 meV and 7.3 meV and are assigned to ℓ = 15,16 and ℓ = 20,21 partial wave resonances, respectively. The experimental results are well reproduced by theoretical calculations with the short-range reaction probability P{sub sr} = 0.035. No clear signature of the orbiting resonances is visible in the branching ratio between NH{sub 3}{sup +} and NH{sub 2}{sup +} formation.

  18. Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry

    SciTech Connect

    Isselhardt, B. H.; Prussin, S. G.; Savina, M. R.; Willingham, D. G.; Knight, K. B.; Hutcheon, I. D.

    2015-12-07

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process between uranium atoms and potential isobars without the aid of chemical purification and separation. The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of the 235U/238U ratio to decrease laser-induced isotopic fractionation. In application, isotope standards are used to identify and correct bias in measured isotope ratios, but understanding laser-induced bias from first-principles can improve the precision and accuracy of experimental measurements. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variations in laser parameters on the measured isotope ratio. The model uses atomic data and empirical descriptions of laser performance to estimate the laser-induced bias expected in experimental measurements of the 235U/238U ratio. Empirical corrections are also included to account for ionization processes that are difficult to calculate from first principles with the available atomic data. As a result, development of this model has highlighted several important considerations for properly interpreting experimental results.

  19. Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry

    DOE PAGES

    Isselhardt, B. H.; Prussin, S. G.; Savina, M. R.; Willingham, D. G.; Knight, K. B.; Hutcheon, I. D.

    2015-12-07

    Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process between uranium atoms and potential isobars without the aid of chemical purification and separation. The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of the 235U/238U ratio to decrease laser-induced isotopic fractionation. In application, isotope standards are used to identify and correct bias in measured isotope ratios, but understanding laser-induced bias from first-principles can improve the precision and accuracy of experimental measurements. A rate equationmore » model for predicting the relative ionization probability has been developed to study the effect of variations in laser parameters on the measured isotope ratio. The model uses atomic data and empirical descriptions of laser performance to estimate the laser-induced bias expected in experimental measurements of the 235U/238U ratio. Empirical corrections are also included to account for ionization processes that are difficult to calculate from first principles with the available atomic data. As a result, development of this model has highlighted several important considerations for properly interpreting experimental results.« less

  20. Investigation of the photoionization properties of pharmaceutically relevant substances by resonance-enhanced multiphoton ionization spectroscopy and single-photon ionization spectroscopy using synchrotron radiation.

    PubMed

    Kleeblatt, Juliane; Ehlert, Sven; Hölzer, Jasper; Sklorz, Martin; Rittgen, Jan; Baumgärtel, Peter; Schubert, Jochen K; Zimmermann, Ralf

    2013-08-01

    The photoionization properties of the pharmaceutically relevant substances amantadine, diazepam, dimethyltryptamine, etomidate, ketamine, mescaline, methadone, and propofol were determined. At beamline U125/2-10m-NIM of the BESSY II synchrotron facility (Berlin, Germany) vacuum ultraviolet (VUV) photoionization spectra were recorded in the energy range 7.1 to 11.9 eV (174.6 to 104.2 nm), showing the hitherto unknown ionization energies and fragmentation appearance energies of the compounds under investigation. Furthermore, (1+1)-resonance-enhanced multiphoton ionization (REMPI) spectra of selected compounds (amantadine, diazepam, etomidate, ketamine, and propofol) were recorded by a continuous scan in the energy range between 3.6 and 5.7 eV (345 to 218 nm) using a tunable optical parametric oscillator (spectral resolution: 0.1 nm) laser system. The resulting REMPI wavelength spectra of these compounds are discussed and put into context with already known UV absorption data. Time-of-flight mass spectrometry was used for ion detection in both experiments. Finally, the implications of the obtained physical-chemical results for potential analytical applications are discussed. In this context, fast detection approaches for the considered compounds from breath gas using photoionization mass spectrometry and a rapid pre-concentration step (e.g., needle trap device) are of interest.

  1. Rotationally Resolved Vacuum Ultraviolet Resonance-Enhanced Multiphoton Ionization (VUV REMPI) of Acetylene via the G̃ Rydberg State.

    PubMed

    Schmidt-May, Alice F; Grütter, Monika; Neugebohren, Jannis; Kitsopoulos, T N; Wodtke, Alec M; Harding, Dan J

    2016-07-14

    We present a 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme for acetylene via the linear G̃ 4sσ (1)Πu Rydberg state, offering partial rotational resolution and the possibility to detect excitation in both the cis- and trans-bending modes. The resonant transition to the G̃ state is driven by a vacuum ultraviolet (VUV) photon, generated by resonant four-wave mixing (FWM) in krypton. Ionization from the short-lived G̃ state then occurs quickly, driven by the high intensity of the residual light from the FWM process. We have observed nine bands in the region between 79 200 cm(-1) and 80 500 cm(-1) in C2H2 and C2D2. We compare our results with published spectra in this region and suggest alternative assignments for some of the Renner-Teller split bands. Similar REMPI schemes should be applicable to other small molecules with picosecond lifetime Rydberg states. PMID:27073931

  2. Two-color resonantly enhanced multiphoton ionization and zero-kinetic-energy photoelectron spectroscopy of jet-cooled indan

    NASA Astrophysics Data System (ADS)

    He, Yonggang; Kong, Wei

    2005-06-01

    We report studies of supersonically cooled indan using two-color resonantly enhanced multiphoton ionization and two-color zero-kinetic-energy photoelectron spectroscopy. With the aid of ab initio and density-functional calculations, vibrational modes of the first electronically excited state of the neutral species and those of the cation have been assigned, and the adiabatic ionization energy has been determined to be 68458±5cm-1. Similar to the ground state and the first electronically excited state of the neutral molecule, the ground state of the cation is also proven to be nonplanar, with an estimated barrier of 213cm-1 and a puckering angle of 15.0°. These conclusions will be discussed in comparison with a previous study of an indan derivative 1,3-benzodioxole.

  3. Ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and ionic radii of element Uus (Z = 117) and astatine.

    PubMed

    Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong

    2010-12-30

    Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds. PMID:21141866

  4. Aging effects on macadamia nut oil studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Proschogo, Nicholas W; Albertson, Peter L; Bursle, Johanna; McConchie, Cameron A; Turner, Athol G; Willett, Gary D

    2012-02-29

    High-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry is successfully used in the detailed molecular analysis of aged macadamia nut oils. The results are consistent with peroxide values, the current industry measure for rancidity, and provide detailed molecular information on the oxidative and hydrolytic degeneration of such oils. Mass analysis of macadamia oil samples stored for extended periods at 6 °C revealed that oils obtained by the cold press method are more susceptible to aging than those obtained using modified Soxhlet or accelerated solvent extraction methods.

  5. Ion microscopy with resonant ionization mass spectrometry : time-of-flight depth profiling with improved isotopic precision.

    SciTech Connect

    Pellin, M. J.; Veryovkin, I. V.; Levine, J.; Zinovev, A.; Davis, A. M.; Stephan, T.; Tripa, C. E.; King, B. V.; Savina, M. R.

    2010-01-01

    There are four generally mutually exclusive requirements that plague many mass spectrometric measurements of trace constituents: (1) the small size (limited by the depth probed) of many interesting materials requires high useful yields to simply detect some trace elements, (2) the low concentrations of interesting elements require efficient discrimination from isobaric interferences, (3) it is often necessary to measure the depth distribution of elements with high surface and low bulk contributions, and (4) many applications require precise isotopic analysis. Resonant ionization mass spectrometry has made dramatic progress in addressing these difficulties over the past five years.

  6. Ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and ionic radii of element Uus (Z = 117) and astatine.

    PubMed

    Chang, Zhiwei; Li, Jiguang; Dong, Chenzhong

    2010-12-30

    Multiconfiguration Dirac-Fock (MCDF) method was employed to calculate the first five ionization potentials, electron affinities, resonance excitation energies, oscillator strengths, and radii for the element Uus and its homologue At. Main valence correlation effects were taken into account. The Breit interaction and QED effects were also estimated. The uncertainties of calculated IPs, EAs, and IR for Uus and At were reduced through an extrapolation procedure. The good consistency with available experimental and other theoretical values demonstrates the validity of the present results. These theoretical data therefore can be used to predict some unknown physicochemical properties of element Uus, Astatine, and their compounds.

  7. Aging effects on macadamia nut oil studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Proschogo, Nicholas W; Albertson, Peter L; Bursle, Johanna; McConchie, Cameron A; Turner, Athol G; Willett, Gary D

    2012-02-29

    High-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry is successfully used in the detailed molecular analysis of aged macadamia nut oils. The results are consistent with peroxide values, the current industry measure for rancidity, and provide detailed molecular information on the oxidative and hydrolytic degeneration of such oils. Mass analysis of macadamia oil samples stored for extended periods at 6 °C revealed that oils obtained by the cold press method are more susceptible to aging than those obtained using modified Soxhlet or accelerated solvent extraction methods. PMID:22268609

  8. Design for an optical cw atom laser

    PubMed Central

    Ashkin, Arthur

    2004-01-01

    A new type of optical cw atom laser design is proposed that should operate at high intensity and high coherence and possibly record low temperatures. It is based on an “optical-shepherd” technique, in which far-off-resonance blue-detuned swept sheet laser beams are used to make new types of high-density traps, atom waveguides, and other components for achieving very efficient Bose–Einstein condensation and cw atom laser operation. A shepherd-enhanced trap is proposed that should be superior to conventional magneto-optic traps for the initial collection of molasses-cooled atoms. A type of dark-spot optical trap is devised that can cool large numbers of atoms to polarization-gradient temperatures at densities limited only by three-body collisional loss. A scheme is designed to use shepherd beams to capture and recycle essentially all of the escaped atoms in evaporative cooling, thereby increasing the condensate output by several orders of magnitude. Condensate atoms are stored in a shepherd trap, protected from absorbing light, under effectively zero-gravity conditions, and coupled out directly into an optical waveguide. Many experiments and devices may be possible with this cw atom laser. PMID:15302937

  9. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments

    SciTech Connect

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo E-mail: xfzheng@mail.ahnu.edu.cn; Zheng, Xianfeng E-mail: xfzheng@mail.ahnu.edu.cn; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-15

    Compared to single ion/electron-optics for velocity-map imaging, a double-focusing lens assembly designed not only allows for mapping velocity imaging of photoelectrons but also allows for investigating the vibrational structure of the intermediate states of neutral species in resonance enhanced multiphoton ionization (REMPI) spectra. In this presentation, in order to record REMPI and photoelectron spectra separately, we have constructed a compact photoelectron velocity-map imaging (VMI) apparatus combined with an opposite linear Wiley-Mclaren time-of-flight mass spectrometer (TOFMS). A mass resolution (m/Δm) of ∼1300 for TOFMS and electron energy resolution (ΔE/E) of 2.4% for VMI have been achieved upon three-photon ionization of Xe atom at 258.00 nm laser wavelength. As a benchmark, in combination of one-color (1 + 1) REMPI and photoelectron imaging of benzene via 6{sup 1} and 6{sup 1}1{sup 1} vibronic levels in the S{sub 1} state, the vibrational structures of the cation and photoelectron angular anisotropy are unraveled. In addition, two-color (1 + 1′) REMPI and photoelectron imaging of aniline was used to complete the accurate measurement of ionization potential (62 271 ± 3 cm{sup −1}). The results suggest that the apparatus is a powerful tool for studying photoionization dynamics in the photoelectron imaging using vibrational-state selected excitation to the intermediate states of neutrals based on REMPI technique.

  10. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments.

    PubMed

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo; Zheng, Xianfeng; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-01

    Compared to single ion/electron-optics for velocity-map imaging, a double-focusing lens assembly designed not only allows for mapping velocity imaging of photoelectrons but also allows for investigating the vibrational structure of the intermediate states of neutral species in resonance enhanced multiphoton ionization (REMPI) spectra. In this presentation, in order to record REMPI and photoelectron spectra separately, we have constructed a compact photoelectron velocity-map imaging (VMI) apparatus combined with an opposite linear Wiley-Mclaren time-of-flight mass spectrometer (TOFMS). A mass resolution (m/Δm) of ∼1300 for TOFMS and electron energy resolution (ΔE/E) of 2.4% for VMI have been achieved upon three-photon ionization of Xe atom at 258.00 nm laser wavelength. As a benchmark, in combination of one-color (1 + 1) REMPI and photoelectron imaging of benzene via 6(1) and 6(1)1(1) vibronic levels in the S1 state, the vibrational structures of the cation and photoelectron angular anisotropy are unraveled. In addition, two-color (1 + 1') REMPI and photoelectron imaging of aniline was used to complete the accurate measurement of ionization potential (62,271 ± 3 cm(-1)). The results suggest that the apparatus is a powerful tool for studying photoionization dynamics in the photoelectron imaging using vibrational-state selected excitation to the intermediate states of neutrals based on REMPI technique. PMID:26133827

  11. The design of double electrostatic-lens optics for resonance enhanced multiphoton ionization and photoelectron imaging experiments

    NASA Astrophysics Data System (ADS)

    Qu, Zehua; Li, Chunsheng; Qin, Zhengbo; Zheng, Xianfeng; Yao, Guanxin; Zhang, Xianyi; Cui, Zhifeng

    2015-06-01

    Compared to single ion/electron-optics for velocity-map imaging, a double-focusing lens assembly designed not only allows for mapping velocity imaging of photoelectrons but also allows for investigating the vibrational structure of the intermediate states of neutral species in resonance enhanced multiphoton ionization (REMPI) spectra. In this presentation, in order to record REMPI and photoelectron spectra separately, we have constructed a compact photoelectron velocity-map imaging (VMI) apparatus combined with an opposite linear Wiley-Mclaren time-of-flight mass spectrometer (TOFMS). A mass resolution (m/Δm) of ˜1300 for TOFMS and electron energy resolution (ΔE/E) of 2.4% for VMI have been achieved upon three-photon ionization of Xe atom at 258.00 nm laser wavelength. As a benchmark, in combination of one-color (1 + 1) REMPI and photoelectron imaging of benzene via 61 and 6111 vibronic levels in the S1 state, the vibrational structures of the cation and photoelectron angular anisotropy are unraveled. In addition, two-color (1 + 1') REMPI and photoelectron imaging of aniline was used to complete the accurate measurement of ionization potential (62 271 ± 3 cm-1). The results suggest that the apparatus is a powerful tool for studying photoionization dynamics in the photoelectron imaging using vibrational-state selected excitation to the intermediate states of neutrals based on REMPI technique.

  12. Comparison of resonance ionization mass spectrometry systems for the determination of 135Cs/137Cs isotope ratios

    NASA Astrophysics Data System (ADS)

    Pibida, Leticia S.; McMahon, C. A.; Nortershauser, Wilfried; Bushaw, Bruce A.

    2002-03-01

    The performance of the Resonance Ionization Mass Spectrometry (RIMS) system at the National Institute of Standards and Technology (NIST) has been compared to a similar system at Pacific Northwest National Laboratory (PNNL). Efficiency and selectivity measurements were performed with both systems and compared to conventional thermal ionization mass spectrometry (TIMS). Determination of the 135Cs / 137Cs ratio was performed using single-resonance excitation 6s 2S1/2 (F equals 4) to 6p 2P3/2 (F equals 5) with an extended cavity diode laser followed by photoionization with the 488 nm line of an argon ion laser. Optical selectivity of more than 2 orders of magnitude against stable 133Cs was attained for 135Cs and 137Cs for both systems with an overall selectivity of 109 for the PNNL system and 108 for the NIST system. Overall efficiencies of 2x10-6 and 5x10-7 were measured for the PNNL and NIST systems respectively. Measurements to determine the chronological age of a nuclear burn-up sample have been performed using both RIMS systems as well as TIMS.

  13. Electron angular distribution in resonance-enhanced two-photon ionization of H{sub 2}{sup +} by ultrashort laser pulses

    SciTech Connect

    Selstoe, S.; Palacios, A.; Fernandez, J.; Martin, F.

    2007-03-15

    We present a theoretical study of the electron angular distribution produced in resonance enhanced two-photon ionization of the H{sub 2}{sup +} molecular ion using ultrashort laser pulses. The method consists in solving the time dependent Schroedinger equation and includes all electronic and vibrational degrees of freedom. Differential (in proton energy and electron emission solid angle) ionization probabilities have been evaluated for various photon energies, laser intensities, and pulse durations. We show that (1+1) resonance-enhanced multiphoton ionization (REMPI) leads to angular distributions significantly different from those produced in direct two-photon ionization. The REMPI process is observed even at photon energies not matching the energy difference between two electronic states in a perfect vertical transition. Interestingly, there is no trace of REMPI effects in the electron angular distribution when the fully differential probabilities are integrated over proton energy.

  14. Molecular photoelectron angular distribution rotations in multi-photon resonant ionization of H{sub 2}{sup +} by circularly polarized ultraviolet laser pulses

    SciTech Connect

    Yuan, Kai-Jun Chelkowski, Szczepan; Bandrauk, André D.

    2015-04-14

    We study effects of pulse durations on molecular photoelectron angular distributions (MPADs) in ultrafast circular polarization ultraviolet resonant ionization processes. Simulations performed on aligned H{sub 2}{sup +} by numerically solving time dependent Schrödinger equations show rotations of MPADs with respect to the molecular symmetry axes. It is found that in multi-photon resonant ionization processes, rotation angles are sensitive to pulse durations, which we attribute to the coherent resonant excitation between the ground state and the intermediate excited electronic state induced by Rabi oscillations. Multi-photon nonresonant and single photon ionization processes are simulated and compared which exhibit a constant rotation angle. An asymmetry parameter is introduced to describe the pulse duration sensitivity by perturbation theory models. Influence of pulse frequency detunings on MPADs is also investigated where oscillations of rotations are absent at long pulse durations due to nonresonance excitation.

  15. Resonance ionization spectroscopy of sodium Rydberg levels using difference frequency generation of high-repetition-rate pulsed Ti:sapphire lasers

    NASA Astrophysics Data System (ADS)

    Naubereit, P.; Marín-Sáez, J.; Schneider, F.; Hakimi, A.; Franzmann, M.; Kron, T.; Richter, S.; Wendt, K.

    2016-05-01

    The generation of tunable laser light in the green to orange spectral range has generally been a deficiency of solid-state lasers. Hence, the formalisms of difference frequency generation (DFG) and optical parametric processes are well known, but the DFG of pulsed solid-state lasers was rarely efficient enough for its use in resonance ionization spectroscopy. Difference frequency generation of high-repetition-rate Ti:sapphire lasers was demonstrated for resonance ionization of sodium by efficiently exciting the well-known D1 and D2 lines in the orange spectral range (both ≈589 nm). In order to prove the applicability of the laser system for its use at resonance ionization laser ion sources of radioactive ion beam facilities, the first ionization potential of Na was remeasured by three-step resonance ionization into Rydberg levels and investigating Rydberg convergences. A result of EIP=41449.455 (6) stat(7) syscm-1 was obtained, which is in perfect agreement with the literature value of EIPlit =41449.451(2)cm-1 . A total of 41 level positions for the odd-parity Rydberg series n f 2F5/2,7/2o for principal quantum numbers of 10 ≤n ≤60 were determined experimentally.

  16. ELECTROSPRAY IONIZATION (ESI) FRAGMENTATIONS AND DIMETHYLDIOXIRANE REACTIVITIES OF THREE DIVERSE LACTAMS HAVING FULL, HALF, AND ZERO RESONANCE ENERGIES

    PubMed Central

    Morgan, Kathleen M.; Ashline, David J.; Morgan, Jessica P.; Greenberg, Arthur

    2014-01-01

    Three lactams having respectively ~20 kcal/mol, ~10 kcal/mol, and 0 kcal/mol of resonance energy have been subjected to electrospray ionization mass spectrometry (ESI/MS) as well as to attempted reaction with dimethyldioxirane (DMDO). The ESI/MS for all three lactams are consistent with fragmentation from the N-protonated, rather than the O-protonated tautomer. Each exhibits a unique fragmentation pathway. DFT calculations are employed to provide insights concerning these pathways. N-Ethyl-2-pyrrolidinone and 1-azabicyclo[3.3.1]nonan-2-one, the full- and half-resonance lactams, are unreactive with DMDO. The “Kirby lactam” (3,5,7-trimethyl-1-azaadamantan-2-one), has zero resonance energy and reacts rapidly with DMDO to generate a mixture of reaction products. The structure assigned to one of these is the 2,2-dihydroxy-N-oxide, thought to be stabilized by intramolecular hydrogen bonding and buttressing by the methyl substituents. A reasonable pathway to this derivative might involve formation of an extremely labile N-oxide, in a purely formal sense an example of the hithertounknown amide N-oxides, followed by hydration with traces of moisture. PMID:24313276

  17. Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for detection of nitrogen containing aliphatic and aromatic compounds: resonance-enhanced multiphoton ionization spectroscopic investigation and on-line analytical application.

    PubMed

    Streibel, T; Hafner, K; Mühlberger, F; Adam, T; Zimmermann, R

    2006-01-01

    Resonance-enhanced multiphoton ionization (REMPI) combined with time-of-flight mass spectrometry (TOFMS) is an analytical method capable of on-line monitoring of trace compounds in complex matrices. A necessary prerequisite for substance selective detection is spectroscopic investigation of the target molecules. Several organic nitrogen compounds comprising aliphatic and aromatic amines, nitrogen heterocyclic compounds, and aromatic nitriles are spectroscopically investigated with a tunable narrow bandwidth optical parametric oscillator (OPO) laser system providing a scannable wavelength range between 220 and 340 nm. These species are known as possible precursors in fuel-NO formation from combustion of solid fuels such as biomass and waste. A newly conceived double inlet system was used in this study, which allows rapid change between effusive and supersonic molecular beams. The resulting REMPI spectra of the compounds are discussed with respect to electronic transitions that could be utilized for a selective ionization of these compounds in complex mixtures such as combustion and process gases. The practicability of this approach is demonstrated by wavelength selected on-line REMPI-TOFMS detection of aniline and cyanonaphthalene in the burning chamber of a waste incineration plant. REMPI mass spectra recorded at different excitation wavelengths as well as variations in time show the utilization of species-selective REMPI-TOFMS detection for on-line monitoring of crucial substances in pollutant formation.

  18. Phonological and Phonetic Asymmetries of Cw Combinations

    ERIC Educational Resources Information Center

    Suh, Yunju

    2009-01-01

    This thesis investigates the relationship between the phonological distribution of Cw combinations, and the acoustic/perceptual distinctiveness between syllables with plain C onsets and with Cw combination onsets. Distributional asymmetries of Cw combinations discussed in this thesis include the avoidance of Cw combinations in the labial consonant…

  19. The Collinear Resonance Ionization Spectroscopy (CRIS) experimental setup at CERN-ISOLDE

    NASA Astrophysics Data System (ADS)

    Cocolios, T. E.; Al Suradi, H. H.; Billowes, J.; Budinčević, I.; de Groote, R. P.; De Schepper, S.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Le Blanc, F.; Lynch, K. M.; Marsh, B. A.; Mason, P. J. R.; Neyens, G.; Papuga, J.; Procter, T. J.; Rajabali, M. M.; Rossel, R. E.; Rothe, S.; Simpson, G. S.; Smith, A. J.; Strashnov, I.; Stroke, H. H.; Verney, D.; Walker, P. M.; Wendt, K. D. A.; Wood, R. T.

    2013-12-01

    The CRIS setup at CERN-ISOLDE is a laser spectroscopy experiment dedicated to the high-resolution study of the spin, hyperfine structure and isotope shift of radioactive nuclei with low production rates (a few per second). It combines the Doppler-free resolution of the in-flight collinear geometry with the high detection efficiency of resonant ionisation. A recent commissioning campaign has demonstrated a 1% experimental efficiency, and as low as a 0.001% non-resonant ionisation. The current status of the experiment and its recent achievements with beams of francium isotopes are reported. The first identified systematic effects are discussed.

  20. Influence of resonance radiation transfer on ionization balance in a positive column plasma

    NASA Astrophysics Data System (ADS)

    Golubovskii, Yu; Syasko, A.

    2016-08-01

    A method of self-consistent solution of charged particles balance equation, which is described by a differential equation of ambipolar diffusion, and an equation of resonance atom balance, which is described by an integral equation of radiation transfer, is proposed. The method is related to a replacement of an integral operator and a differential operator by a system of linear algebraic equations. The difference between a precise solution and a solution in the approximation of the effective resonance transition probability is shown. The influence of highest diffusion and radiation modes becomes apparent during transition to a contracted state.

  1. Measurement and calculation of the Stark-broadening parameters for the resonance lines of singly ionized calcium and magnesium.

    NASA Technical Reports Server (NTRS)

    Jones, W. W.; Sanchez, A.; Greig, J. R.; Griem, H. R.

    1972-01-01

    The electron-impact-broadened profiles of the resonance lines of singly ionized calcium and magnesium have been measured using an electromagnetically driven shock tube and a rapid-scanning Fabry-Perot spectrometer. For an electron density of 10 to the 17th power per cu cm and a temperature of 19,000 K, we found the Lorentzian half-width of the Ca+ line to be 0.086 A plus or minus 10% and of the Mg+ line to be 0.044 A plus or minus 10%. Using the quantum-mechanical theory of Barnes and Peach and our semiclassical calculation for the calcium lines, we found that the temperature dependence of the theoretical curves is close to that measured, although both theories predict actual values which are somewhat large.

  2. Structural characterization of phospholipids by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Marto, J A; White, F M; Seldomridge, S; Marshall, A G

    1995-11-01

    Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode.

  3. New odd-parity high-lying energy levels of the europium atom by resonance ionization spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakhate, S. G.; Razvi, M. A. N.; Bhale, G. L.; Ahmad, S. A.

    1996-04-01

    Odd-parity energy levels of the neutral europium atom (Eu I) have been investigated by employing both single-colour and two-colour stepwise laser excitation using the technique of resonance ionization spectroscopy in a heat-pipe thermionic diode system. Fifty-two new odd-parity energy levels of Eu I have been found in the energy region 40 575 - 43 410 0953-4075/29/8/009/img1. The J values for most of these new energy levels have been assigned unambiguously. In addition to this, 19 odd levels which were reported earlier, in the region of our present study, have also been investigated; the assignments of J values to nine of these levels have been confirmed and four levels, which had no unique J assignments, have been assigned definite J values.

  4. Kinetic modeling of evolution of 3 + 1:Resonance enhanced multiphoton ionization plasma in argon at low pressures

    SciTech Connect

    Tholeti, Siva Sashank; Alexeenko, Alina A.; Shneider, Mikhail N.

    2014-06-15

    We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5 Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10 s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

  5. New Rydberg states of gas-phase aluminum halides observed by resonance-enhanced multiphoton ionization spectroscopy

    SciTech Connect

    Hudgens, J.W.; Dearden, D.V.; Johnson, R.D. III

    1993-12-31

    The authors report detection and characterization of AlF and AlCl using 1+2, 2=1, 2+2, 3+1, and 3+2 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. REMPI Spectra of AlF reveal 13 new Rydberg states that lie between 70,000 and 77,000 cm{sup {minus}1}. These new states, in combination with previously known states, form six Rydberg series. Least-squares fitting of the Rydberg series to the Rydberg equation yields the precise adiabatic ionization potential, IP{sub a}(AlF) = 9.729 {+-} 0.001 eV. Vibrational intervals of the new Rydberg states are about 25% greater than those of AlF (X {sup 1}{Sigma}{sup +}), with most lying between 930-980 cm{sup {minus}1}. REMPI spectra of AlCl reveal new Rydberg states that lie between 54000 and 60000 cm{sup {minus}1}. Vibrational intervals of these new Rydberg states are about 25% greater than those of AlCl (X {sup 1}{Sigma}{sup +}), with most lying between 570-600 cm{sup {minus}1}.

  6. Kinetic modeling of evolution of 3 + 1:Resonance enhanced multiphoton ionization plasma in argon at low pressures

    NASA Astrophysics Data System (ADS)

    Tholeti, Siva Sashank; Shneider, Mikhail N.; Alexeenko, Alina A.

    2014-06-01

    We present numerical kinetic modeling of generation and evolution of the plasma produced as a result of resonance enhanced multiphoton ionization (REMPI) in Argon gas. The particle-in-cell/Monte Carlo collision (PIC/MCC) simulations capture non-equilibrium effects in REMPI plasma expansion by considering the major collisional processes at the microscopic level: elastic scattering, electron impact ionization, ion charge exchange, and recombination and quenching for metastable excited atoms. The conditions in one-dimensional (1D) and two-dimensional (2D) formulations correspond to known experiments in Argon at a pressure of 5 Torr. The 1D PIC/MCC calculations are compared with the published results of local drift-diffusion model, obtained for the same conditions. It is shown that the PIC/MCC and diffusion-drift models are in qualitative and in reasonable quantitative agreement during the ambipolar expansion stage, whereas significant non-equilibrium exists during the first few 10 s of nanoseconds. 2D effects are important in the REMPI plasma expansion. The 2D PIC/MCC calculations produce significantly lower peak electron densities as compared to 1D and show a better agreement with experimentally measured microwave radiation scattering.

  7. Detection of NO and NO(2) by (2 + 2) resonance-enhanced multiphoton ionization and photoacoustic spectroscopy near 454 nm.

    PubMed

    Pastel, R L; Sausa, R C

    1996-07-20

    Trace concentrations of NO and NO(2) are detected with a dye laser operating near 454 nm. NO is detected by a (2 + 2) resonance-enhanced multiphoton ionization process by means of NO A(2)Σ+-X(2)Π(0, 0) transitions with miniature electrodes, and NO(2) is detected by a one-photon absorption photoacoustic process by means of NO(2)A¯' (2)B(1)(0, 8, 0)- X¯ (2)A(1)(0, 0, 0) transitions with a miniature microphone. Rotationally resolved excitation spectra show that the spectral resolution is sufficiently high to identify these species at 1 atm. The technique's analytical merits are evaluated as functions of concentration, pressure, and laser intensities. Low laser intensities favor NO(2) photoacoustic detection whereas high laser intensities favor NO ionization. Limits of detection (signal-to-noise ratio 3) of 160 parts in 10(9) for NO and 400 parts in 10(9) for NO(2) are determined at 1 atm for a 10-s integration time. Signal response and noise analyses show that three decades of NO/NO(2) mixtures can be measured with a computational relative error in concentration that is three times the relative error in measuring the NO and NO(2) signals.

  8. Plume composition and evolution in multicomponent ices using resonant two-step laser ablation and ionization mass spectrometry.

    PubMed

    Henderson, Bryana L; Gudipati, Murthy S

    2014-07-24

    The composition and evolution of plumes generated in a resonant infrared (IR) laser desorption of low-temperature ices is investigated via a recently developed two-step laser desorption and ionization mass spectrometry (2S-LAIMS) technique where a neutral plume is ejected by an IR laser pulse and ionized by a UV laser pulse for analysis via time-of-flight mass spectrometry. By varying the delay between the lasers, we can construct a complete time-resolved model of the ejected plume components. We found that water ices containing mixtures of polar and nonpolar analytes displayed complex mass spectral profiles that varied as the plume evolved. In these samples, the low-volatility polar analytes and clusters were restricted to the early part of the plume, whereas volatile or nonpolar analytes were spread throughout the plume. The distributions of low-volatility polar species, clusters, and impurities from the copper substrate were well-represented by single Maxwell-like distributions centered at high velocities (600-800 m s(-1)), while nonpolar, volatile species contained two distinct components, indicating both ablation and thermal desorption processes. Characterization of plume distributions can therefore provide new insight into an analyte's chemical identity and can aid in assignment of otherwise ambiguous signals in the mass spectra.

  9. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

  10. Resonance enhanced multiphoton ionization photoelectron spectroscopy and pulsed field ionization via the F 1Delta 2(vscript=0) and f 3Delta 2(vscript=0) Rydberg states of HCl

    NASA Astrophysics Data System (ADS)

    de Beer, E.; Buma, W. J.; de Lange, C. A.

    1993-09-01

    In this paper, we report the first rotationally resolved one- and two-color resonance enhanced multiphoton ionization photoelectron spectroscopy (REMPI-PES) study of the HCl molecule. The agreement between our experimental branching ratios and theoretical investigations is excellent. We also report the first zero kinetic energy pulsed field ionization (ZEKE-PFI) experiments carried out in a ``magnetic bottle'' electron spectrometer. A direct comparison is made between ZEKE-PFI and REMPI-PES spectra for ionization via several rotational levels of the F 1Δ2(v'=0) and f 3Δ2(v'=0) Rydberg states of HCl. Large differences in both the spin-orbit and rotational branching ratios are found between the ZEKE-PFI and REMPI-PES spectra. These differences can be understood qualitatively on the basis of rotational and spin-orbit autoionization mechanisms.

  11. Ionizing Radiation Detectors Based on Ge-Doped Optical Fibers Inserted in Resonant Cavities

    PubMed Central

    Avino, Saverio; D’Avino, Vittoria; Giorgini, Antonio; Pacelli, Roberto; Liuzzi, Raffaele; Cella, Laura; De Natale, Paolo; Gagliardi, Gianluca

    2015-01-01

    The measurement of ionizing radiation (IR) is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of IR on germanosilicate optical fibers. A piece of Ge-doped fiber enclosed between two fiber Bragg gratings (FBGs) is irradiated with gamma radiation generated by a 6 MV medical linear accelerator. With respect to other FBG-based IR dosimeters, here the sensor is only the bare fiber without any special internal structure. A near infrared laser is frequency locked to the cavity modes for high resolution measurement of radiation induced effects on the fiber optical parameters. In particular, we observe a variation of the fiber thermo-optic response with the radiation dose delivered, as expected from the interaction with Ge defect centers, and demonstrate a detection limit of 360 mGy. This method can have an impact in those contexts where low radiation doses have to be measured both in small volumes or over large areas, such as radiation therapy and radiation protection, while bare optical fibers are cheap and disposable. PMID:25686311

  12. Microwave reflectometer ionization sensor

    NASA Technical Reports Server (NTRS)

    Seals, Joseph; Fordham, Jeffrey A.; Pauley, Robert G.; Simonutti, Mario D.

    1993-01-01

    The development of the Microwave Reflectometer Ionization Sensor (MRIS) Instrument for use on the Aeroassist Flight Experiment (AFE) spacecraft is described. The instrument contract was terminated, due to cancellation of the AFE program, subsequent to testing of an engineering development model. The MRIS, a four-frequency reflectometer, was designed for the detection and location of critical electron density levels in spacecraft reentry plasmas. The instrument would sample the relative magnitude and phase of reflected signals at discrete frequency steps across 4 GHz bandwidths centered at four frequencies: 20, 44, 95, and 140 GHz. The sampled data would be stored for later processing to calculate the distance from the spacecraft surface to the critical electron densities versus time. Four stepped PM CW transmitter receivers were located behind the thermal protection system of the spacecraft with horn antennas radiating and receiving through an insulating tile. Techniques were developed to deal with interference, including multiple reflections and resonance effects, resulting from the antenna configuration and operating environment.

  13. Resonant two-photon ionization spectroscopy of jet-cooled OsN: 520-418 nm

    NASA Astrophysics Data System (ADS)

    Garcia, Maria A.; Morse, Michael D.

    2011-09-01

    The optical transitions of supersonically cooled OsN have been investigated in the range from 19 200 to 23 900 cm-1 using resonant two-photon ionization spectroscopy. More than 20 vibronic bands were observed, 17 of which were rotationally resolved and analyzed. The ground state is confirmed to be 2Δ5/2, deriving from the 1σ2 2σ2 1π4 1δ3 3σ2 electronic configuration. The X 2Δ5/2 ground state rotational constant for 192Os14N was found to be B0 = 0.491921(34) cm-1, giving r0 = 1.62042(6) Å (1σ error limits). The observed bands were grouped into three band systems with Ω' = 7/2 and four with Ω' = 3/2, corresponding to the three 2Φ7/2 and four 2Π3/2 states expected from the 1σ2 2σ2 1π4 1δ3 3σ1 2π1 and 1σ2 2σ2 1π4 1δ2 3σ2 2π1 electronic configurations. In addition, two interacting upper states with Ω' = 5/2 were observed, one of which is thought to correspond to a 1σ2 2σ2 1π3 1δ3 3σ2 2π1, 2Δ5/2 state. Spectroscopic constants are reported for all of the observed states, and comparisons to related molecules are made. The ionization energy of OsN is estimated as IE(OsN) = 8.80 ± 0.06 eV.

  14. High-resolution accurate mass measurements of biomolecules using a new electrospray ionization ion cyclotron resonance mass spectrometer.

    PubMed

    Winger, B E; Hofstadler, S A; Bruce, J E; Udseth, H R; Smith, R D

    1993-07-01

    A novel electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer based on a 7-T superconducting magnet was developed for high-resolution accurate mass measurements of large biomolecules. Ions formed at atmospheric pressure using electrospray ionization (ESI) were transmitted (through six differential pumping stages) to the trapped ion cell maintained below 10(-9) torr. The increased pumping speed attainable with cryopumping (> 10(5) L/s) allowed brief pressure excursions to above 10(-4) torr, with greatly enhanced trapping efficiencies and subsequent short pumpdown times, facilitating high-resolution mass measurements. A set of electromechanical shutters were also used to minimize the effect of the directed molecular beam produced by the ES1 source and were open only during ion injection. Coupled with the use of the pulsed-valve gas inlet, the trapped ion cell was generally filled to the space charge limit within 100 ms. The use of 10-25 ms ion injection times allowed mass spectra to be obtained from 4 fmol of bovine insulin (Mr 5734) and ubiquitin (Mr 8565, with resolution sufficient to easily resolve the isotopic envelopes and determine the charge states. The microheterogeneity of the glycoprotein ribonuclease B was examined, giving a measured mass of 14,898.74 Da for the most abundant peak in the isotopic envelope of the normally glycosylated protein (i.e., with five mannose and two N-acetylglucosamine residues (an error of approximately 2 ppm) and an average error of approximately 1 ppm for the higher glycosylated and various H3PO4 adducted forms of the protein. Time-domain signals lasting in excess of 80 s were obtained for smaller proteins, producing, for example, a mass resolution of more than 700,000 for the 4(+) charge state (m/z 1434) of insulin. PMID:24227643

  15. Oil spill source identification by principal component analysis of electrospray ionization Fourier transform ion cyclotron resonance mass spectra.

    PubMed

    Corilo, Yuri E; Podgorski, David C; McKenna, Amy M; Lemkau, Karin L; Reddy, Christopher M; Marshall, Alan G; Rodgers, Ryan P

    2013-10-01

    One fundamental challenge with either acute or chronic oil spills is to identify the source, especially in highly polluted areas, near natural oil seeps, when the source contains more than one petroleum product or when extensive weathering has occurred. Here we focus on heavy fuel oil that spilled (~200,000 L) from two suspected fuel tanks that were ruptured on the motor vessel (M/V) Cosco Busan when it struck the San Francisco-Oakland Bay Bridge in November 2007. We highlight the utility of principal component analysis (PCA) of elemental composition data obtained by high resolution FT-ICR mass spectrometry to correctly identify the source of environmental contamination caused by the unintended release of heavy fuel oil (HFO). Using ultrahigh resolution electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry, we uniquely assigned thousands of elemental compositions of heteroatom-containing species in neat samples from both tanks and then applied principal component analysis. The components were based on double bond equivalents for constituents of elemental composition, CcHhN1S1. To determine if the fidelity of our source identification was affected by weathering, field samples were collected at various intervals up to two years after the spill. We are able to identify a suite of polar petroleum markers that are environmentally persistent, enabling us to confidently identify that only one tank was the source of the spilled oil: in fact, a single principal component could account for 98% of the variance. Although identification is unaffected by the presence of higher polarity, petrogenic oxidation (weathering) products, future studies may require removal of such species by anion exchange chromatography prior to mass spectral analysis due to their preferential ionization by ESI.

  16. Rotationally resolved photoelectron spectra in resonance enhanced multiphoton ionization of HCl via the F 1Δ2 Rydberg state

    NASA Astrophysics Data System (ADS)

    Wang, Kwanghsi; McKoy, V.

    1991-12-01

    Results of studies of rotational ion distributions in the X 2Π3/2 and X 2Π1/2 spin-orbit states of HCl+ resulting from (2+1') resonance enhanced multiphoton ionization (REMPI) via the S(0) branch of the F 1Δ2 Rydberg state are reported and compared with measured threshold-field-ionization zero-kinetic-energy spectra reported recently [K. S. Haber, Y. Jiang, G. Bryant, H. Lefebvre-Brion, and E. R. Grant, Phys. Rev. A (in press)]. These results show comparable intensities for J+=3/2 of the X 2Π3/2 ion and J+=1/2 of the X 2Π1/2 ion. Both transitions require an angular momentum change of ΔN=-1 upon photoionization. To provide further insight into the near-threshold dynamics of this process, we also show rotationally resolved photoelectron angular distributions, alignment of the ion rotational levels, and rotational distributions for the parity components of the ion rotational levels. About 18% population is predicted to occur in the (+) parity component, which would arise from odd partial-wave contributions to the photoelectron matrix element. This behavior is similar to that in (2+1) REMPI via the S(2) branch of the F 1Δ2 state of HBr and was shown to arise from significant l mixing in the electronic continuum due to the nonspherical molecular ion potential. Rotational ion distributions resulting from (2+1) REMPI via the S(10) branch of the F 1Δ2 state are also shown.

  17. CW RFQ fabrication and engineering

    SciTech Connect

    Schrage, D.; Young, L.; Roybal, P.

    1998-12-31

    The design and fabrication of a four-vane RFQ to deliver a 100 mA CW proton beam at 6.7 MeV is described. This linac is an Oxygen-Free Electrolytic (OFE) copper structure 8 m in length and was fabricated using hydrogen furnace brazing as the joining technology.

  18. Excitation of the {sup 229m}Th nuclear isomer via resonance conversion in ionized atoms

    SciTech Connect

    Karpeshin, F. F.; Trzhaskovskaya, M. B.

    2015-09-15

    Pressing problems concerning the optical pumping of the 7.6-eV {sup 229m}Th nuclear isomer, which is a candidate for a new nuclear optical reference point for frequencies, are examined. Physics behind the mechanism of the two-photon optical pumping of the isomer is considered. It is shown that, irrespective of the pumping scheme, a dominant contribution comes, in accord with what was proven earlier for the 3.5-eV isomer, from the resonance 8s–7s transition. Details of an optimum experimental scheme are discussed. It is shown that, after isomer excitation, the atom involved remains with a high probability in an excited state at an energy of about 0.5 eV rather than in the ground state, the required energy of the two photons being equal to the energy of the nuclear level plus the energy of the lowest 7s state of the atom. The estimated pumping time is about 1.5 s in the case where the field strength of each laser is 1 V/cm.

  19. Vacuum compatible sample positioning device for matrix assisted laser desorption∕ionization Fourier transform ion cyclotron resonance mass spectrometry imaging.

    PubMed

    Aizikov, Konstantin; Smith, Donald F; Chargin, David A; Ivanov, Sergei; Lin, Tzu-Yung; Heeren, Ron M A; O'Connor, Peter B

    2011-05-01

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in ∼1 × 10(-8) mbar vacuum. The range of motion is set to 100 mm × 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption∕ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The "oversampling" MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.

  20. Observation of the 5p Rydberg states of sulfur difluoride radical by resonance-enhanced multiphoton ionization spectroscopy.

    PubMed

    Zhang, Qun; Zhou, Xiaoguo; Li, Quanxin; Yu, Shuqin; Ma, Xingxiao

    2008-04-14

    Sulfur difluoride radicals in their ground state have been produced by a "laser-free" pulsed dc discharge of the SF6Ar gas mixtures in a supersonic molecular beam and detected by mass-selective resonance-enhanced multilphoton ionization (REMPI) spectroscopy in the wavelength range of 408-420 nm. Analyses of the (3+1) REMPI excitation spectrum have enabled identification of three hitherto unknown Rydberg states of this radical. Following the Rydberg state labeling in our previous work [see J. Phys. Chem. A 102, 7233 (1998)], these we label the K(5p1) [nu 0-0=71 837 cm(-1), omega'1(a1 sym str)=915 cm(-1)], L(5p2) [nu 0-0=72 134 cm(-1), omega'1(a1 sym str)=912 cm(-1)], and M(5p3) [nu 0-0=72 336 cm(-1), omega'1(a1 sym str)=926 cm(-1)] Rydberg states, respectively. [Origins, relative to the lowest vibrational level of the X 1A1 ground state, and vibrational frequencies of the symmetric S-F stretching mode are suggested by the numbers in brackets.] Photofragmentation process of SF2+-->SF+ +F that relates to the REMPI spectrum was discussed. PMID:18412444

  1. Characterization of vegetable oils: detailed compositional fingerprints derived from electrospray ionization fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Wu, Zhigang; Rodgers, Ryan P; Marshall, Alan G

    2004-08-25

    Adulteration of vegetable oil is of concern for both commercial and health reasons. Compositional based fingerprints can potentially reveal both the oil source and its possible adulteration. Here, electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) resolves and identifies literally thousands of distinct chemical components of commercial canola, olive, and soybean oils, without extraction or other wet chemical separation pretreatment. In negative-ion ESI FT-ICR MS, the acidic components of soybean oil are easily distinguished from those of canola and olive oil based on relative abundances of C(18) fatty acids, whereas olive oil differs from canola and soybean oil based on relative abundances of tocopherols. In positive-ion ESI FT-ICR MS, the three oils are readily distinguished according to the relative abundances of di- and triacylglycerols with various numbers of double bonds in the fatty acid chains. We demonstrate the detection of soybean oil as an adulterant of olive oil, based on relative abundances of members of each of several chemical families. We suggest that the detailed chemical compositions of vegetable oils can be used to characterize them and to detect and identify adulterants. PMID:15315364

  2. The use of ultraviolet resonance Raman spectroscopy in the analysis of ionizing-radiation-induced damage in DNA.

    PubMed

    Shaw, C P; Jirasek, A

    2009-04-01

    Ultraviolet resonance Raman spectroscopy (UVRRS) was used to determine damage done in both calf-thymus DNA (CT-DNA) and a short stranded DNA oligomer (SS-DNA) due to ionizing radiation from a medical (60)Co radiation therapy unit used in the treatment of cancer. Spectra were acquired at incident UV wavelengths of 248, 257, and 264 nm in order to utilize the differences in UVRR cross-sections of the bases with wavelength. Through the analysis of difference spectra between irradiated and unirradiated DNA at each of the incident UV wavelengths, damage to CT- and SS-DNA was observed and identified. Significant radiation-induced increases in the difference spectra of the CT-DNA indicated disruption of the stable, stacked structure of its bases, as well as the disruption of Watson-Crick hydrogen bonds between the base pairs. Base unstacking was not as evident in the SS-DNA, while radiation-induced spectral decreases suggest disruption of the structure of the nucleotides. As demonstrated, UVRRS has the ability to highlight contributions from specific moieties with the use of varying incident UV wavelengths, thus enhancing the already information-rich content of the Raman spectra.

  3. Temperature sensitivity of molecular oxygen resonant-enhanced multiphoton ionization spectra involving the C 3Π g intermediate state

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Zhang, Zhili; Adams, Steven F.

    2016-05-01

    The technique of measuring O2 rotational temperature by coherent microwave Rayleigh scattering from resonance-enhanced multiphoton ionization (Radar REMPI) has been studied to determine temperature sensitivity and range. The molecular oxygen Rydberg state of ( {3sσ } )C{{}3}Πg ( {v^' } = 2} ) has been selected as the intermediate state in the 2 + 1 REMPI process, which is known to provide a relatively strong REMPI signal. Rotational-resolved spectra representing the two-photon C{{}3}Πg ( {v^' } = 2} ) leftarrow leftarrow X{{}3}Σ g^{ - } ( {v^' ' } = 0} ) transition have been obtained under several gas conditions including pure oxygen, air-like syngas, ambient air, and flame environments from room temperature ( 300 K) to flame temperature ( 1700 K). An O2 REMPI spectral model has been developed to simulate the experimental spectral line intensity distribution which is dependent on the O2 ground-state temperature. The model has been verified at a low-temperature condition ( 5 K) and then applied to various oxygen environments over an extended temperature range with an overall error of less than ±10 %. The current O2 REMPI spectral model is an improvement over a previously reported version in both accuracy and the quantity of lines fit to provide rotational temperature measurements. This work details an optimized model that fits simulated spectra to full experimental spectral bands over various conditions with a wide temperature range, including both low temperature (<300 K) and high temperature ranges (>1300 K).

  4. Evaluating the Aging of Multiple Emulsions Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry.

    PubMed

    Tsuda, Yukihiro; Uchimura, Tomohiro

    2016-01-01

    Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry was applied to measurements of multiple emulsions with no pretreatment; a method for the quantitative evaluation of aging was proposed. We prepared water-in-oil-in-water (W/O/W) multiple emulsions containing toluene and m-phenylenediamine. The samples were measured immediately following both preparation and after having been stirred for 24 h. Time profiles of the peak areas for each analyte species were obtained, and several intense spikes for toluene could be detected from each sample after stirring, which suggests that the concentration of toluene in the middle phase had increased during stirring. On the other hand, in the case of a W/O/W multiple emulsion containing phenol and m-phenylenediamine, spikes for m-phenylenediamine, rather than phenol, were detected after stirring. In the present study, the time-profile data were converted into a scatter plot in order to quantitatively evaluate the aging. As a result, the ratio of the plots where strong signal intensities of toluene were detected increased from 8.4% before stirring to 33.2% after stirring for 24 h. The present method could be a powerful tool for evaluating multiple emulsions, such as studies on the kinetics of the encapsulation and release of active ingredients. PMID:27396662

  5. Characterization of vegetable oils: detailed compositional fingerprints derived from electrospray ionization fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Wu, Zhigang; Rodgers, Ryan P; Marshall, Alan G

    2004-08-25

    Adulteration of vegetable oil is of concern for both commercial and health reasons. Compositional based fingerprints can potentially reveal both the oil source and its possible adulteration. Here, electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) resolves and identifies literally thousands of distinct chemical components of commercial canola, olive, and soybean oils, without extraction or other wet chemical separation pretreatment. In negative-ion ESI FT-ICR MS, the acidic components of soybean oil are easily distinguished from those of canola and olive oil based on relative abundances of C(18) fatty acids, whereas olive oil differs from canola and soybean oil based on relative abundances of tocopherols. In positive-ion ESI FT-ICR MS, the three oils are readily distinguished according to the relative abundances of di- and triacylglycerols with various numbers of double bonds in the fatty acid chains. We demonstrate the detection of soybean oil as an adulterant of olive oil, based on relative abundances of members of each of several chemical families. We suggest that the detailed chemical compositions of vegetable oils can be used to characterize them and to detect and identify adulterants.

  6. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    SciTech Connect

    Aizikov, Konstantin; Lin, Tzu-Yung; Smith, Donald F.; Heeren, Ron M. A.; Chargin, David A.; Ivanov, Sergei; O'Connor, Peter B.

    2011-05-15

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in {approx}1 x 10{sup -8} mbar vacuum. The range of motion is set to 100 mm x 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The ''oversampling'' MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.

  7. Zero kinetic energy photoelectron spectroscopy of jet cooled benzo[a]pyrene from resonantly enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Harthcock, Colin; Han, Fangyuan; Kong, Wei

    2011-12-01

    We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[a]pyrene (BaP) via resonantly enhanced multiphoton ionization (REMPI). Our analysis concentrates on the vibrational modes of the first excited state (S1) and those of the ground cationic state (D0). Similar to pyrene, another peri-condensed polycyclic aromatic hydrocarbon we have investigated, the first two electronically excited states of BaP exhibit extensive configuration interactions. However, the two electronic states are of the same symmetry, hence vibronic coupling does not introduce any out-of-plane modes in the REMPI spectrum, and Franck-Condon analysis is qualitatively satisfactory. The ZEKE spectra from the in-plane modes observed in the REMPI spectrum demonstrate strong propensity in preserving the vibrational excitation of the intermediate state. Although several additional bands in combination with the vibrational mode of the intermediate state are identifiable, they are much lower in intensity. This observation implies that the molecular structure of BaP has a tremendous capability to accommodate changes in charge density. All observed bands of the cation are IR active, establishing the role of ZEKE spectroscopy in mapping out far infrared bands for astrophysical applications.

  8. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    PubMed Central

    Aizikov, Konstantin; Smith, Donald F.; Chargin, David A.; Ivanov, Sergei; Lin, Tzu-Yung; Heeren, Ron M. A.; O’Connor, Peter B.

    2011-01-01

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in ∼1 × 10–8 mbar vacuum. The range of motion is set to 100 mm × 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The “oversampling” MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter. PMID:21639522

  9. Evaluation of Resonance Ionization Mass Spectrometry for the Determination of 135Cs / 137Cs Isotope Ratios in Low-Level Samples

    SciTech Connect

    Pibida, L.; Nortershauser, W.; Hutchinson, J.M.R.; Bushaw, Bruce A.

    2001-01-01

    Determination of the ratio of 135Cs / 137Cs radioisotopes using resonance ionization mass spectrometry (RIMS) has been evaluated for measurements requiring extreme background suppression characteristics. Single-resonance excitation of Cs 6s 2S1/2 (F = 4) ® 6p 2P3/2 (F¢ = 5) with an extended cavity diode laser was followed by photoionization with the 488 nm line of an argon ion laser. While the principal objective was to avoid isobaric interferences, an optical selectivity of ~ 3 orders of magnitude against stable 133Cs was attained for both 135Cs and 137Cs. The overall RIMS efficiency was found to be ~ 2´10-6 with a combined (mass spectrometer and laser) selectivity of ~ 1010. The performance with respect to efficiency, selectivity, and isobar suppression has been compared to conventional thermal ionization mass spectrometry (TIMS). Measurements to determine the chronological age of a burn-up sample have been performed using both methods.

  10. Vibrations of the S{sub 1} state of fluorobenzene-h{sub 5} and fluorobenzene-d{sub 5} via resonance-enhanced multiphoton ionization (REMPI) spectroscopy

    SciTech Connect

    Harris, Joe P.; Andrejeva, Anna; Tuttle, William D.; Wright, Timothy G.; Pugliesi, Igor; Schriever, Christian

    2014-12-28

    We report resonance-enhanced multiphoton ionization spectra of the isotopologues fluorobenzene-h{sub 5} and fluorobenzene-d{sub 5}. By making use of quantum chemical calculations, the changes in the wavenumber of the vibrational modes upon deuteration are examined. Additionally, the mixing of vibrational modes both between isotopologues and also between the two electronic states is discussed. The isotopic shifts lead to dramatic changes in the appearance of the spectrum as vibrations shift in and out of Fermi resonance. Assignments of the majority of the fluorobenzene-d{sub 5} observed bands are provided, aided by previous results on fluorobenzene-h{sub 5}.

  11. Three-photon resonance ionization of atomic Mn in a hot-cavity laser ion source using Ti:sapphire lasers

    SciTech Connect

    Liu, Y.; Gottwald, T.; Mattolat, C.; Wendt, K.

    2015-05-08

    We have demonstrated three-photon resonance ionization of atomic manganese (Mn) in a hot-cavity ion source using Ti: sapphire lasers. Three-step ionization schemes employing different intermediate levels and Rydberg or autoionizing (AI) states in the final ionization step are established. Strong AI resonances were observed via the 3d54s5s f6S5/2 level at 49 415.35 cm-1, while Rydberg transitions were reached from the 3d54s4d e 6D9/2,7/2,5/2) levels at around 47 210 cm-1. Analyses of the strong Rydberg transitions associated with the 3d54s4d e 6D7/2 lower level indicate that they belong to the dipole-allowed 4d → nf69/2,7/2,5/2 series converging to the 3d54s 7S3 ground state of Mn II. From this series, an ionization potential of 59 959.56 ± 0.01 cm-1 is obtained for Mn. At high ion source temperatures the semi-forbidden 4d → nf8F°9/2,7/2,5/2 series was also observed. The overall ionization efficiency for Mn has been measured to be about 0.9% when using the strong AI transition in the third excitation step and 0.3% when employing an intense Rydberg transition. Experimental data indicate that the ionization efficiency was limited by the interaction of Mn atoms with ion source materials at high temperatures.

  12. Three-photon resonance ionization of atomic Mn in a hot-cavity laser ion source using Ti:sapphire lasers

    DOE PAGES

    Liu, Y.; Gottwald, T.; Mattolat, C.; Wendt, K.

    2015-05-08

    We have demonstrated three-photon resonance ionization of atomic manganese (Mn) in a hot-cavity ion source using Ti: sapphire lasers. Three-step ionization schemes employing different intermediate levels and Rydberg or autoionizing (AI) states in the final ionization step are established. Strong AI resonances were observed via the 3d54s5s f6S5/2 level at 49 415.35 cm-1, while Rydberg transitions were reached from the 3d54s4d e 6D9/2,7/2,5/2) levels at around 47 210 cm-1. Analyses of the strong Rydberg transitions associated with the 3d54s4d e 6D7/2 lower level indicate that they belong to the dipole-allowed 4d → nf6F°9/2,7/2,5/2 series converging to the 3d54s 7S3 groundmore » state of Mn II. From this series, an ionization potential of 59 959.56 ± 0.01 cm-1 is obtained for Mn. At high ion source temperatures the semi-forbidden 4d → nf8F°9/2,7/2,5/2 series was also observed. The overall ionization efficiency for Mn has been measured to be about 0.9% when using the strong AI transition in the third excitation step and 0.3% when employing an intense Rydberg transition. Experimental data indicate that the ionization efficiency was limited by the interaction of Mn atoms with ion source materials at high temperatures.« less

  13. Laser ablation with resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for determining aromatic lignin volatilization products from biomass

    NASA Astrophysics Data System (ADS)

    Mukarakate, Calvin; Scheer, Adam M.; Robichaud, David J.; Jarvis, Mark W.; David, Donald E.; Ellison, G. Barney; Nimlos, Mark R.; Davis, Mark F.

    2011-03-01

    We have designed and developed a laser ablation/pulsed sample introduction/mass spectrometry platform that integrates pyrolysis (py) and/or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of He, then skimmed and introduced into an ionization region. One color resonance-enhanced multiphoton ionization (1+1 REMPI) is used, resulting in highly selective detection of lignin subunits from complex vapors of biomass materials. The spectra obtained by py-REMPI-TOFMS and LA-REMPI-TOFMS display high selectivity and decreased fragmentation compared to spectra recorded by an electron impact ionization molecular beam mass spectrometer (EI-MBMS). The laser ablation method demonstrates the ability to selectively isolate and volatilize specific tissues within the same plant material and then detect lignin-based products from the vapors with enhanced sensitivity. The identification of select products observed in the LA-REMPI-TOFMS experiment is confirmed by comparing their REMPI wavelength scans with that of known standards.

  14. Laser ablation with resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for determining aromatic lignin volatilization products from biomass.

    PubMed

    Mukarakate, Calvin; Scheer, Adam M; Robichaud, David J; Jarvis, Mark W; David, Donald E; Ellison, G Barney; Nimlos, Mark R; Davis, Mark F

    2011-03-01

    We have designed and developed a laser ablation∕pulsed sample introduction∕mass spectrometry platform that integrates pyrolysis (py) and∕or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of He, then skimmed and introduced into an ionization region. One color resonance-enhanced multiphoton ionization (1+1 REMPI) is used, resulting in highly selective detection of lignin subunits from complex vapors of biomass materials. The spectra obtained by py-REMPI-TOFMS and LA-REMPI-TOFMS display high selectivity and decreased fragmentation compared to spectra recorded by an electron impact ionization molecular beam mass spectrometer (EI-MBMS). The laser ablation method demonstrates the ability to selectively isolate and volatilize specific tissues within the same plant material and then detect lignin-based products from the vapors with enhanced sensitivity. The identification of select products observed in the LA-REMPI-TOFMS experiment is confirmed by comparing their REMPI wavelength scans with that of known standards. PMID:21456715

  15. Status of the Project-X CW Linac Design

    SciTech Connect

    Ostiguy, J-F.; Solyak, N.; Berrutti, P.; Carneiro, J.P.; Lebedev, V.; Nagaitsev, S.; Saini, A.; Stheynas, B.; Yakovlev, V.P.; /Fermilab

    2012-05-01

    Project-X is a proposed proton accelerator complex at Fermilab that would provide particle beams to support a diversified experimental program at the intensity frontier. As currently envisioned, the complex would employ a CW superconducting linac to accelerate a 1 mA average, 5 mA peak H{sup -} beam from 2.1 MeV to 3 GeV. A second superconducting linac, operating in pulsed mode would ultimately accelerate a small fraction of this beam up to 8 GeV. The CW linac is based on five families of resonators operating at three frequencies: half-wave (1 family at 162.5 MHz), spoke (2 families at 325 MHz) and elliptical (2 families at 650 MHz). Accelerating and focusing elements are assembled in cryomodules separated by short warm sections. A long open region ({approx} 15 m) allows beam extraction at 1 GeV in support of a nuclear experimental program. In this paper, we present the latest iteration of the CW linac baseline lattice. We also briefly compare it to an alternative where the 162.5 half-wave resonators are replaced with 325 MHz spoke resonators.

  16. CW laser pumped emerald laser

    SciTech Connect

    Shand, M.L.; Lai, S.T.

    1984-02-01

    A CW laser-pumped emerald laser is reported. A 34 percent output power slope efficiency is observed with longitudinal pumping by a krypton laser in a nearly concentric cavity. The laser has been tuned from 728.8 to 809.0 nm. Losses in emerald are larger than those of alexandrite determined in a similar cavity. The present data also indicate that the excited state absorption minimum is shifted from that of alexandrite. 13 references.

  17. Laser induced fluorescence and resonant two-photon ionization spectroscopy of jet-cooled 1-hydroxy-9,10-anthraquinone

    NASA Astrophysics Data System (ADS)

    Cho, Sung Haeng; Huh, Hyun; Kim, Hyung Min; Kim, Choong Ik; Kim, Nam Joon; Kim, Seong Keun

    2005-01-01

    We carried out laser induced fluorescence and resonance enhanced two-color two-photon ionization spectroscopy of jet-cooled 1-hydroxy-9,10-anthraquinone (1-HAQ). The 0-0 band transition to the lowest electronically excited state was found to be at 461.98 nm (21 646 cm-1). A well-resolved vibronic structure was observed up to 1100 cm-1 above the 0-0 band, followed by a rather broad absorption band in the higher frequency region. Dispersed fluorescence spectra were also obtained. Single vibronic level emissions from the 0-0 band showed Stokes-shifted emission spectra. The peak at 2940 cm-1 to the red of the origin in the emission spectra was assigned as the OH stretching vibration in the ground state, whose combination bands with the C=O bending and stretching vibrations were also seen in the emission spectra. In contrast to the excitation spectrum, no significant vibronic activity was found for low frequency fundamental vibrations of the ground state in the emission spectrum. The spectral features of the fluorescence excitation and emission spectra indicate that a significant change takes place in the intramolecular hydrogen bonding structure upon transition to the excited state, such as often seen in the excited state proton (or hydrogen) transfer. We suggest that the electronically excited state of interest has a double minimum potential of the 9,10-quinone and the 1,10-quinone forms, the latter of which, the proton-transferred form of 1-HAQ, is lower in energy. On the other hand, ab initio calculations at the B3LYP/6-31G(d,p) level predicted that the electronic ground state has a single minimum potential distorted along the reaction coordinate of tautomerization. The 9,10-quinone form of 1-HAQ is the lowest energy structure in the ground state, with the 1,10-quinone form lying ˜5000 cm-1 above it. The intramolecular hydrogen bond of the 9,10-quinone was found to be unusually strong, with an estimated bond energy of ˜13 kcal/mol (˜4500 cm-1), probably due to

  18. High-resolution field desorption/ionization fourier transform ion cyclotron resonance mass analysis of nonpolar molecules.

    PubMed

    Schaub, Tanner M; Hendrickson, Christopher L; Qian, Kuangnan; Quinn, John P; Marshall, Alan G

    2003-05-01

    We report the first field desorption ionization broadband high-resolution (m/Deltam(50%) approximately 65 000) mass spectra. We have interfaced a field ionization/field desorption source to a home-built 9.4-T FT-ICR mass spectrometer. The instrumental configuration employs convenient sample introduction (in-source liquid injection) and external ion accumulation. We demonstrate the utility of this configuration by generating high-resolution positive-ion mass spectra of C(60) and a midboiling crude oil distillate. The latter contains species not accessible by common soft-ionization methods, for example, low-voltage electron ionization, electrospray ionization, and matrix-assisted laser desorption/ionization. The present work demonstrates significant advantages of FI/FD FT-ICR MS for analysis of nonpolar molecules in complex mixtures.

  19. Resonance Ionization of Heavy Noble Gases: The Potential of KR and Xe Measurements from Single Pre-Solar Grains

    NASA Astrophysics Data System (ADS)

    Thonnard, N.

    1995-09-01

    measure noble gases from fourteen individual "X" SiC grains, previously identified by ion microprobe analysis, was unsuccessful with the 2,000 132Xe atom detection limit of the mass spectrometer [12,13]. From the Kr concentration measurements of SiC particles KJF by Lewis et al. [6], a 2 micrometer diameter particle will on average contain 134 Kr atoms. If only 4% of the SiC grains contain the majority of the noble gas atoms, then a single gas rich grain will contain 3,350 Kr atoms, or 12, 75, 385, 398, 1910, and 580 atoms for 78Kr through 86Kr, respectively. The Xe single-grain abundances would be similar. Resonance ionization, an emerging laser-based element analysis technique, is being harnessed to a wide variety of problems in which minute quantities of a particular element need to be measured efficiently in the presence of an overwhelmingly larger background of other materials [14]. By utilizing lasers tuned to specific atomic energy levels of the analyte element, ions are produced selectively in a mass spectrometer with much higher efficiency than possible using conventional methods, such as electron bombardment, thermal ionization, or ion sputtering. In a static resonance ionization system for noble gases, the combination of high ionization efficiency and sample concentrator results in an extremely fast (~3 min. detection half-life vs. ~60 min. for conventional systems) analyzer with a detection limit of ~100 85Kr atoms [15]. In addition to the almost complete absence of interferences, the short analysis time significantly reduces the background contribution of outgassing in the mass spectrometer. Although using a less efficient laser scheme resulting in slightly slower analyses, a similar system has recently been completed and dedicated to extraterrestrial Xe measurements [16]. At the newly formed Institute for Rare Isotope Measurements [17], the noble gas equipment that had previously been at Atom Sciences [14,15] is being re-installed and upgraded to provide

  20. Ionization Potentials for Isoelectronic Series.

    ERIC Educational Resources Information Center

    Agmon, Noam

    1988-01-01

    Presents a quantitative treatment of ionization potentials of isoelectronic atoms. By looking at the single-electron view of calculating the total energy of an atom, trends in the screening and effective quantum number parameters are examined. Approaches the question of determining electron affinities. (CW)

  1. Fine- and hyperfine-structure effects in molecular photoionization. II. Resonance-enhanced multiphoton ionization and hyperfine-selective generation of molecular cations

    NASA Astrophysics Data System (ADS)

    Germann, Matthias; Willitsch, Stefan

    2016-07-01

    Resonance-enhanced multiphoton ionization (REMPI) is a widely used technique for studying molecular photoionization and producing molecular cations for spectroscopy and dynamics studies. Here, we present a model for describing hyperfine-structure effects in the REMPI process and for predicting hyperfine populations in molecular ions produced by this method. This model is a generalization of our model for fine- and hyperfine-structure effects in one-photon ionization of molecules presented in Paper I [M. Germann and S. Willitsch, J. Chem. Phys. 145, 044314 (2016)]. This generalization is achieved by covering two main aspects: (1) treatment of the neutral bound-bound transition including the hyperfine structure that makes up the first step of the REMPI process and (2) modification of our ionization model to account for anisotropic populations resulting from this first excitation step. Our findings may be used for analyzing results from experiments with molecular ions produced by REMPI and may serve as a theoretical background for hyperfine-selective ionization experiments.

  2. Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

    USGS Publications Warehouse

    Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

    2013-01-01

    Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

  3. Identification and DNA typing of two Cw7 alleles (Cw*0702 and Cw*0704) in Japanese, with the corrected sequence of Cw*0702.

    PubMed

    Wang, H; Tokunaga, K; Ishikawa, Y; Asahina, A; Kuwata, S; Akaza, T; Tadokoro, K; Shibata, Y; Takiguchi, M; Juji, T

    1996-01-01

    Two alleles encoding HLA-Cw7 antigens, tentatively called C7J1 and C7J2, have been identified in Japanese using a PCR-SSCP method. The nucleotide sequence of full-length C7J1 cDNAs showed a high degree of homology to the reported Cw*0702 sequence except in exon 1. We then resequenced the allele carried by the cell line JY in which Cw*0702 was first identified, according to a request from the WHO Nomenclature Committee. The results revealed complete identity between the corrected Cw*0702 sequence and the C7J1 sequence. On the other hand, the C7J2 sequence was completely identical to the reported Cw*0704 sequence. Sequences specific for Cw*0702 and Cw*0704 were confirmed using PCR-RFLP and PCR-SSO methods. Moreover, association analysis with other HLA locus alleles showed positive associations of Cw*0702 with HLA-B7, -B39, and -B67 and of Cw*0704 with HLA-B70 in Japanese.

  4. Large Scale CW ECRH Systems: Meeting a Challenge

    SciTech Connect

    Erckmann, V.; Braune, H.; Laqua, H. P.; Marushchenko, N. B.; Michel, G.; Kasparek, W.; Plaum, B.; Lechte, C.; Stuttgart, IPF; Petelin, M. I.; Lubiako, L.; Bruschi, A.; D'Arcangelo, O.; Bin, W.; Van Den Braber, R.; Doelman, N.; Gantenbein, G.; Thumm, M.

    2011-12-23

    Electron Cyclotron Resonance Heating (ECRH) systems for next step-fusion devices like W7-X and ITER operate in CW-mode and provide a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configuration and MHD control. The request for many different sophisticated applications results in a growing complexity of the systems. This is in conflict with the request for high availability, reliability, and maintainability, which arises from DEMO demands. 'Advanced' ECRH-components must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW facility of an ITER relevant size and is used as a test bed for such components. Results on improvements of gyrotrons, transmission components and launchers are presented together with proposals for future developments.

  5. Effects of non-adiabatic coupling in photofragmentation of CO(2) using resonance enhanced multiphoton ionization techniques

    NASA Astrophysics Data System (ADS)

    Dharmasena, Kushlani Chandima

    1997-07-01

    We observed Resonance Enhanced Multiphoton Ionization (REMPI) spectra of nf2ΠΩ Rydberg states of CO2 for n=4 to 8. In addition, we also did a laser power dependence study of these states for n=5 to 7. We compared our results to two other studies by Johnson and coworkers and Dobber and coworkers. In the present study we observed that dissociation rate increased with increasing frequency. Also, we observed a clear difference in rates of dissociation for the two spin-orbit components of each nf state. This difference was not consistent, in some states the /Omega=1/2 component dissociated more while in the others /Omega=3/2 dissociated more. When comparing with Dobber and coworkers' REMPI-Photoelectron Spectra (REMPI-PES), a good correlation between the observed symmetric vibrational progressions and our dissociation rates was noticed. We also found that these rates stayed remarkably constant for different powers of the laser even though the production of CO+ ions required more photons than CO2+ ions. From this observation we came to the conclusion that the two-photon transition was saturated. What was surprising was, the amount of CO2+ ions observed despite the fact that the two-photon transition X 2Πg/to/to[ C]2Σg+ was saturated. The observed ratio of CO+/CO2+ ratio never was lower than 6. These observations led us to believe that CO+ ions were predominantly made by predissociation rather than direct dissociation. We propose that the two- photon transition is X 2Πg/to/to[ C]2Σg+ followed by predissociation of the C2ΣG+ state. In our model, predissociation must occur through a potential barrier in the C2Σg+ state which is on the order of an electron volt above the dissociation limit. We estimated the mean lifetime of this state to be about 600 psec by using the ratio of CO+/CO2+ from our spectra. This model explains two other phenomena observed in REMPI spectra. First is the observation of increased dissociation with increasing principal quantum number in the

  6. Upgrade of the resonance ionization laser ion source at ISOLDE on-line isotope separation facility: New lasers and new ion beamsa)

    NASA Astrophysics Data System (ADS)

    Fedosseev, V. N.; Berg, L.-E.; Fedorov, D. V.; Fink, D.; Launila, O. J.; Losito, R.; Marsh, B. A.; Rossel, R. E.; Rothe, S.; Seliverstov, M. D.; Sjödin, A. M.; Wendt, K. D. A.

    2012-02-01

    The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; replacement of the old homemade dye lasers by new commercial dye lasers; installation of a complementary Ti:Sapphire laser system. The combined dye and Ti:Sapphire laser system with harmonics is capable of generating beams at any wavelength in the range of 210-950 nm. In total, isotopes of 31 different elements have been selectively laser-ionized and separated at ISOLDE, including recently developed beams of samarium, praseodymium, polonium, and astatine.

  7. Upgrade of the resonance ionization laser ion source at ISOLDE on-line isotope separation facility: new lasers and new ion beams.

    PubMed

    Fedosseev, V N; Berg, L-E; Fedorov, D V; Fink, D; Launila, O J; Losito, R; Marsh, B A; Rossel, R E; Rothe, S; Seliverstov, M D; Sjödin, A M; Wendt, K D A

    2012-02-01

    The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; replacement of the old homemade dye lasers by new commercial dye lasers; installation of a complementary Ti:Sapphire laser system. The combined dye and Ti:Sapphire laser system with harmonics is capable of generating beams at any wavelength in the range of 210-950 nm. In total, isotopes of 31 different elements have been selectively laser-ionized and separated at ISOLDE, including recently developed beams of samarium, praseodymium, polonium, and astatine. PMID:22380244

  8. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal

    PubMed Central

    Zuber, Jan; Kroll, Marius M.; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  9. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal.

    PubMed

    Zuber, Jan; Kroll, Marius M; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  10. Fraunhofer-like diffracted lateral photoelectron momentum distributions of H2+ in charge-resonance-enhanced ionization in strong laser fields

    NASA Astrophysics Data System (ADS)

    Xin, Lin; Qin, Han-Cheng; Wu, Wan-Yang; He, Feng

    2015-12-01

    For H2+ at the critical internuclear distance where the charge-resonance-enhanced ionization is most prominent, the lateral photoelectron momentum distribution presents the Fraunhofer-like diffraction pattern: a central disk surrounded by one or more rings. We study this phenomenon by simulating the time-dependent Schrödinger equation and unveil the mechanism: the stretched molecule constructs an interatomic Coulomb potential, which works as a circular aperture and diffracts the electron when it travels between two nuclei. This distinct lateral photoelectron momentum distribution offers another perspective to look into molecular structures.

  11. Resonance Enhanced Multi-Photon Ionization and Uv-Uv Hole-Burning Spectroscopic Studies of Jet-Cooled Acetanilide Derivatives

    NASA Astrophysics Data System (ADS)

    Moon, Ceol Joo; Min, Ahreum; Ahn, Ahreum; Lee, Seung Jun; Choi, Myong Yong; Kim, Seong Keun

    2013-06-01

    Conformational investigations and photochemistry of jet-cooled methacetine (MA) and phenacetine (PA) using one color resonant two-photon ionization (REMPI), UV-UV hole-burning and IR-dip spectroscopy are presented. MA and PA are derivatives of acetanilide, substituted by methoxyl, ethoxyl group in the para position of acetanilide, respectively. Moreover, we have investigated conformational information of the acetanilide derivatives (AAP, MA and PA)-water. In this work, we will present and discuss the solvent effects of the hydroxyl group of acetanilide derivatives in the excited state.

  12. The coupling of direct analysis in real time ionization to Fourier transform ion cyclotron resonance mass spectrometry for ultrahigh-resolution mass analysis.

    PubMed

    Rummel, Julia L; McKenna, Amy M; Marshall, Alan G; Eyler, John R; Powell, David H

    2010-03-01

    Direct Analysis in Real Time (DART) is an ambient ionization technique for mass spectrometry that provides rapid and sensitive analyses with little or no sample preparation. DART has been reported primarily for mass analyzers of low to moderate resolving power such as quadrupole ion traps and time-of-flight (TOF) mass spectrometers. In the current work, a custom-built DART source has been successfully coupled to two different Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers for the first time. Comparison of spectra of the isobaric compounds, diisopropyl methylphosphonate and theophylline, acquired by 4.7 T FT-ICR MS and TOF MS, demonstrates that the TOF resolving power can be insufficient for compositionally complex samples. 9.4 T FT-ICR MS yielded the highest mass resolving power yet reported with DART ionization for 1,2-benzanthracene and 9,10-diphenylanthracene. Polycyclic aromatic hydrocarbons exhibit a spatial dependence in ionization mechanisms between the DART source and the mass spectrometer. The feasibility of analyzing a variety of samples was established with the introduction and analysis of food products and crude oil samples. DART FT-ICR MS provides complex sample analysis that is rapid, highly selective and information-rich, but limited to relatively low-mass analytes.

  13. Angular and internal state distributions of H2 (+) generated by (2 + 1) resonance enhanced multiphoton ionization of H2 using time-of-flight mass spectrometry.

    PubMed

    Perreault, William E; Mukherjee, Nandini; Zare, Richard N

    2016-06-01

    We report direct measurement of the anisotropy parameter β for the angular distribution of the photoelectron and photoion in (2 + 1) resonance enhanced multiphoton ionization process of H2 X (1)Σg (+) (v = 0, J = 0) molecules through the intermediate H2 E,F (1)Σg (+) (v' = 0, J' = 0) level (λ = 201.684 nm) using a time-of-flight mass spectrometer. The time-of-flight spectra were recorded as the direction of polarization of the ionizing laser was varied with respect to the flight axis of the H2 molecular beam and were fitted to an angular distribution in an appropriately rotated coordinate system with the z-axis oriented along the time-of-flight axis. The anisotropy parameter β was found to be 1.72 ± 0.13 by fitting the time-of-flight spectra and agreed with previous measurements. Using secondary ionization with a delayed laser pulse of different wavelength, we also determined the vibrational energy distribution of the ions, showing that 98% ± 4% of the ions are generated in their ground vibrational state, in agreement with the calculated Franck-Condon factors between the H2 E,F (1)Σg (+) (v' = 0) and H2 (+) X (1)Σg (+) (v″) vibrational levels.

  14. Capillary column gas chromatography, resonance enhanced multiphoton ionization, time-of-flight mass spectrometry, laser-induced fluorescence, flame ionization detection system for the determination of polynuclear aromatic compounds in complex mixtures

    SciTech Connect

    Dobson, R.L.M.

    1986-01-01

    A method is reached to fully characterize the polynuclear aromatic hydrocarbons (PAC) that have been deemed to be highly mutagenic or carcinogenic. A multidimensional, laser-based analytical instrument has been developed that, when utilized to the full extent of its capabilities could be the solution to this complex analytical problem. The overall technique is termed Capillary Column Gas Chromatography, Resonance Enhanced Multiphoton Ionization, Time-of-Flight Mass Spectrometry, Laser-induced Fluorescence, with parallel Flame Ionization Detection (CC/GC-REMPI-TOF/MS-LIF-FID). This system combines the selectivity of two complementary laser-based methods, REMPI and LIF, with an extremely powerful and proven analytical tool, GC/MS. The GC effluent passes through the ion source of a TOF/MS, where it is interrogated by a tunable ultraviolet laser beam. Thus, PAC and other absorbing species may be selectively excited and/or ionized in the presence of nonabsorbing components. All laser-analyte interaction products (actions, electrons, and photons) are simultaneously monitored utilizing the TOF/MS, a total electron current detector (TECD), and a LIF detector. The main advantage of this technique is that all analytically useful data for each absorbing chromatographic eluent may be collected on-the-fly. The simultaneous availability of this information simplifies the characterization task. The present absolute detection limits for several PAC have been determined to be low picogram range. Also, a linear dynamic range of approximately four orders of magnitude has been established for the TECD, indicating that this technique is both sensitive and quantitative. Further, the use of deuterated analogs, of selected PAC, as internal reference standards greatly assists in quantitation.

  15. Evaluation of combined matrix-assisted laser desorption/ionization time-of-flight and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry experiments for peptide mass fingerprinting analysis.

    PubMed

    da Silva, David; Wasselin, Thierry; Carré, Vincent; Chaimbault, Patrick; Bezdetnaya, Lina; Maunit, Benoît; Muller, Jean-François

    2011-07-15

    Peptide Mass Fingerprinting (PMF) is still of significant interest in proteomics because it allows a large number of complex samples to be rapidly screened and characterized. The main part of post-translational modifications is generally preserved. In some specific cases, PMF suffers from ambiguous or unsuccessful identification. In order to improve its reliability, a combined approach using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) was evaluated. The study was carried out on bovine serum albumin (BSA) digest. The influence of several important parameters (the matrix, the sample preparation method, the amount of the analyte) on the MOWSE score and the protein sequence coverage were evaluated to allow the identification of specific effects. A careful investigation of the sequence coverage obtained by each kind of experiment ensured the detection of specific peptides for each experimental condition. Results highlighted that DHB-FTICRMS and DHB- or CHCA-TOFMS are the most suited combinations of experimental conditions to achieve PMF analysis. The association (convolution) of the data obtained by each of these techniques ensured a significant increase in the MOWSE score and the protein sequence coverage.

  16. Sequential CW-EPR image acquisition with 760-MHz surface coil array.

    PubMed

    Enomoto, Ayano; Hirata, Hiroshi

    2011-04-01

    This paper describes the development of a surface coil array that consists of two inductively coupled surface-coil resonators, for use in continuous-wave electron paramagnetic resonance (CW-EPR) imaging at 760 MHz. To make sequential EPR image acquisition possible, we decoupled the surface coils using PIN-diode switches, to enable the shifting of the resonators resonance frequency by more than 200 MHz. To assess the effectiveness of the surface coil array in CW-EPR imaging, two-dimensional images of a solution of nitroxyl radicals were measured with the developed coil array. Compared to equivalent single coil acquired images, we found the visualized area to be extended approximately 2-fold when using the surface coil array. The ability to visualize larger regions of interest through the use of a surface coil array, may offer great potential in future EPR imaging studies. PMID:21320789

  17. Quantitative determination of H2, HD, and D2 internal-state distributions by (2+1) resonance-enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Rinnen, Klaus-Dieter; Buntine, Mark A.; Kliner, Dahv A. V.; Zare, Richard N.; Huo, Winifred M.

    1991-07-01

    Results are presented of an experimental study of (2+1) resonance-enhanced multiphoton ionization (REMPI) detection of H2, HD, and D2 via the E,F two-photon transition, in which the relationship between ion signals and quantum-state populations was determined by calibration against a thermal effusive source. Vibrational and rotational correction factors were obtained for 102 rovibrational levels for v-double-prime = 0, 1, and 2 and for J-double-prime ranging from 0 to 17. These correction factors make it possible to convert ion signals into relative quantum-state populations without relying on a theoretical description of the (2+1) REMPI process.

  18. Quantitative determination of H2, HD, and D2 internal-state distributions by (2+1) resonance-enhanced multiphoton ionization

    NASA Technical Reports Server (NTRS)

    Rinnen, Klaus-Dieter; Buntine, Mark A.; Kliner, Dahv A. V.; Zare, Richard N.; Huo, Winifred M.

    1991-01-01

    Results are presented of an experimental study of (2+1) resonance-enhanced multiphoton ionization (REMPI) detection of H2, HD, and D2 via the E,F two-photon transition, in which the relationship between ion signals and quantum-state populations was determined by calibration against a thermal effusive source. Vibrational and rotational correction factors were obtained for 102 rovibrational levels for v-double-prime = 0, 1, and 2 and for J-double-prime ranging from 0 to 17. These correction factors make it possible to convert ion signals into relative quantum-state populations without relying on a theoretical description of the (2+1) REMPI process.

  19. Isotope pattern evaluation for the reduction of elemental compositions assigned to high-resolution mass spectral data from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Stoll, Norbert; Schmidt, Enrico; Thurow, Kerstin

    2006-12-01

    The number of possible chemical formulae assigned to an accurate determined mass was significantly reduced by comparing spectral and theoretical isotope patterns based on mass measurement obtained with an ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR-MS) at high field intensity (7 T). Reduction is performed by rating congruency between experimental and theoretical pattern intensity and mass, and filtering out compositions with insufficient user-definable results. The methods used for isotope pattern simulation, peak searching, and comparison will be briefly described and evaluated on molecule ion signals of 25 compounds (300-1000 Da) applying a mass accuracy of +/-5 ppm, a set of eight elements with constant constraints (C0-200H0-1000N0-15O0-15S0-2Cl0-2Br0-2Ru0-1), natural isotope abundances and experimental resolution (full width at half maximum).

  20. Resonance-enhanced two-photon ionization mass spectroscopy of ephedrine: Indication for a state-selective fragmentation in a flexible molecule

    NASA Astrophysics Data System (ADS)

    Karaminkov, R.; Chervenkov, S.; Härter, P.; Neusser, H. J.

    2007-07-01

    The vibronic structure of the S 1 ← S 0 spectrum of ephedrine was measured by resonance-enhanced two-photon ionization spectroscopy with mass resolution under cold molecular beam conditions. The spectra recorded at four different mass channels, m/ z = 165 (parent), 58, and the hitherto unknown 71, 85 fragment ions show dissimilar vibronic fine structure and the observed mass pattern strongly depends on the selected intermediate vibrational state. This points to an intermediate state-selected process resulting in a different fragmentation mass pattern. Ab initio calculations at the MP2/6-311++G ∗∗ level demonstrate that the AG (a) conformer is more stable by 238 cm -1 than the next stable GG (a) conformer.

  1. Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry.

    PubMed

    Dorfner, Ralph; Ferge, Thomas; Kettrup, Antonius; Zimmermann, Ralf; Yeretzian, Chahan

    2003-09-10

    The formation of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting was monitored in real-time, using resonance enhanced multiphoton ionization and time-of-flight mass spectrometry. A model is proposed, based on two connected reaction channels. One channel, termed the "low activation energy" channel, consists of ester hydrolysis of 5-FQA followed by decarboxylation of the ferulic acid to form 4-vinylguaiacol, and finally polymerization at the vinyl group to form partly insoluble polymers (coffee melanoidins). The second "high activation energy" channel opens up once the beans have reached higher temperatures. It leads to formation of guaiacol, via oxidation of 4-vinylguaiacol, and subsequently to phenol and other phenolic VOCs. This work aims at developing strategies to modify the composition of coffee flavor compounds based on the time-temperature history during roasting. PMID:12952431

  2. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (GALDI-FTICR-MS)

    SciTech Connect

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; J. Michelle Kotler; Jill R. Scott

    2008-10-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) has been employed to determine how effectively bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO-2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition ofC18H39O7Na-. Anatural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination were estimated to be 3 parts per trillion or~7 zeptomoles (10-21) per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTICR-MS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  3. Observation of rotamers of m-aminobenzoic acid: Zero kinetic energy photoelectron and hole-burning resonantly enhanced multiphoton ionization spectroscopy

    NASA Astrophysics Data System (ADS)

    He, Yonggang; Wu, Chengyin; Kong, Wei

    2004-11-01

    We report studies of supersonically cooled m-aminobenzoic acid using two-color resonantly enhanced multiphoton ionization (REMPI) and two-color zero kinetic energy (ZEKE) photoelectron spectroscopy. Two conformers have been identified and characterized using the hole-burning method in the REMPI experiment. With the aid of ab initio and density functional calculations, vibrational modes of the first electronically excited state (S1) of the neutral species and those of the ground state cation (D0) have been assigned, and the adiabatic ionization potentials have been determined for both conformers. The REMPI spectra are dominated by in-plane motions of the substituents and ring deformation modes. A propensity of Δv=0, where Δv is the change in vibrational quantum number from the S1 to the D0 state, is observed in the ZEKE spectra. The origin of this behavior is discussed in the context of electron back donation from the two substituents in the excited state and in the cationic state. Comparisons of these results with those of p-aminobenzoic acid will be analyzed.

  4. Dating the Martian meteorite Zagami by the 87Rb-87Sr isochron method with a prototype in situ resonance ionization mass spectrometer

    PubMed Central

    Scott Anderson, F; Levine, Jonathan; Whitaker, Tom J

    2015-01-01

    RATIONALE The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ∼270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ∼1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. METHODS We demonstrate the first use of laser ablation resonance ionization mass spectrometry for 87Rb-87Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. RESULTS To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained 87Rb-87Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an 87Rb-87Sr age for this specimen of 360 ±90 Ma. CONCLUSIONS Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The

  5. Capillary column gas chromatography, resonance enhanced multiphoton ionization, time-of-flight mass spectrometry laser-induced fluorescence, flame ionization detection system for the determination of polynuclear aromatic compounds in complex mixtures

    SciTech Connect

    Dobson, R.L.M.

    1986-06-01

    Of the thousands of chemical compounds that have been deemed mutagenic or carcinogenic, it is generally agreed that the polynuclear aromatic hydrocarbons (PAC) are among the most potent. Because of the wide range of potency of PAC, even among geometric isomers and substitutional derivatives, it is important to fully characterize these samples. This task is a formidable one, usually requiring elaborate sample clean-up and fractionation prior to analysis. A multidimensional, laser-based analytical instrument has been developed that, when utilized to the full extent of its capabilities, could be the solution to this complex analytical problem. The overall technique is termed Capillary Column Gas Chromatography, Resonance Enhanced Multiphoton Ionization, Time-Of-Flight Mass Spectrometry, Laser-induced Fluorescence, with parallel Flame Ionization Detection (CC/GC-REMPI-TOF/MS-LIF-FID). This system combines the selectivity and sensitivity of two complementary laser-based methods, REMPI and LIF, with an extremely powerful and proven analytical tool, GC/MS. The GC effluent passes through the ion source of a TOF/MS, where it is interrogated by a tunable ultraviolet laser beam. All laser-analyte interaction products (cations, electrons, and photons) are simultaneously monitored utilizing the TOF/MS, a total electron current detector (TECD), and a LIF detector. The simultaneous availability of this information simplifies the characterization task. The present absolute detection limits for several PAC have been determined to be in the low picogram range. Also, a linear dynamic range of approximately four orders of magnitude has been established for the TECD, indicating that this technique is both sensitive and quantitative. Further, the use of deuterated analogs, of selected PAC, as internal reference standards greatly assists in quantitation. 219 refs., 37 figs., 13 tabs.

  6. Instrumentation and method for ultrahigh resolution field desorption ionization fourier transform ion cyclotron resonance mass spectrometry of nonpolar species.

    PubMed

    Schaub, Tanner M; Hendrickson, Christopher L; Quinn, John P; Rodgers, Ryan P; Marshall, Alan G

    2005-03-01

    We describe the construction and application of a 9.4-T FT-ICR mass spectrometer interfaced to a commercial field desorption ion source for high-resolution, high-mass accuracy measurements of nonpolar species. The FT-ICR MS instrument includes a liquid injection field desorption ionization source, octopole ion guides, external octopole ion trap capable of an axial potential gradient for ion ejection, capacitively coupled open cylindrical ion trap, and pulsed gas valve for ion cooling. Model compound responses with regard to various source and instrument conditions provide a basis for interpretation of broadband mass spectra of complex mixtures. As an example, we demonstrate broadband speciation of a Gulf Coast crude oil, with respect to numerous heteroatomic classes, compound types (rings plus double bonds), and carbon number distributions.

  7. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric and semi-empirical calculations study of five isoflavone aglycones.

    PubMed

    Madeira, Paulo J Amorim; Borges, Carlos M; Florêncio, M Helena

    2010-12-15

    Five isoflavones, daidzein, genistein, formononetin, prunetin and biochanin A, known for their biological properties, are investigated by electrospray ionization mass spectrometry in the positive ion mode. The most probable protonation sites are determined taking into account semi-empirical calculations using the PM6 Hamiltonian. Fragmentation mechanisms are proposed based on accurate mass measurements, MS(3) experiments and supported by the semi-empirical calculations. Some of the fragmentation pathways were found to be dependent on the substitution pattern of the B-ring and the ions afforded by these fragmentations can be considered as diagnostic. It was possible to distinguish between prunetin and biochanin A, two isobaric isoflavone aglycones included in this study. Furthermore, a comparison of the fragmentation patterns of genistein and biochanin A, two isoflavones, with those of their flavone counterparts, apigenin and acacetin, enabled us to identify some key ions mainly due to structural features, allowing distinction to be made between these two classes of compounds.

  8. Volume nanograting formation in laser-silica interaction as a result of the 1D plasma-resonance ionization instability

    NASA Astrophysics Data System (ADS)

    Gildenburg, V. B.; Pavlichenko, I. A.

    2016-08-01

    The initial stage of the small-scale ionization-induced instability developing inside the fused silica volume exposed to the femtosecond laser pulse is studied as a possible initial cause of the self-organized nanograting formation. We have calculated the spatial spectra of the instability with the electron-hole diffusion taken into account for the first time and have found that it results in the formation of some hybrid (diffusion-wave) 1D structure with the spatial period determined as the geometrical mean of the laser wavelength and characteristic diffusion length of the process considered. Near the threshold of the instability, this period occurs to be approximately equal to the laser half-wavelength in the silica, close to the one experimentally observed.

  9. Rb‐Sr resonance ionization geochronology of the Duluth Gabbro: A proof of concept for in situ dating on the Moon

    PubMed Central

    Levine, Jonathan; Whitaker, Tom J.

    2015-01-01

    Rationale We report new 87Rb‐87Sr isochron data for the Duluth Gabbro, obtained with a laser ablation resonance ionization mass spectrometer that is a prototype spaceflight instrument. The gabbro has a Rb abundance and a range of Rb/Sr ratios that are similar to those of KREEP‐rich basalts found on the nearside of the Moon. Dating of previously un‐sampled young lunar basalts, which generally have a KREEP‐rich composition, is critical for understanding the bombardment history of the Moon since 3.5 Ga, which in turn informs the chronology of the solar system. Measurements of lunar analogs like the Duluth Gabbro are a proof of concept for in situ dating of rocks on the Moon to constrain lunar history. Methods Using the laser ablation resonance ionization mass spectrometer we ablated hundreds of locations on a sample, and at each one measured the relative abundances of the isotopes of Rb and Sr. A delay between the resonant photoionization processes separates the elements in time, eliminating the potential interference between 87Rb and 87Sr. This enables the determination of 87Rb‐87Sr isochron ages without sophisticated sample preparation that would be impractical in a spaceflight context. Results We successfully dated the Duluth Gabbro to 800 ± 300 Ma using traditional isochron methods like those used in our earlier analysis of the Martian meteorite Zagami. However, we were able to improve this to 1100 ± 200 Ma, an accuracy of <1σ, using a novel normalization approach. Both these results agree with the age determined by Faure et al. in 1969, but our novel normalization improves our precision. Conclusions Demonstrating that this technique can be used for measurements at this level of difficulty makes ~32% of the lunar nearside amenable to in situ dating, which can complement or supplement a sample return program. Given these results and the scientific value of dating young lunar basalts, we have recently proposed a spaceflight mission called the Moon Age

  10. Design of 57.5 MHz CW RFQ for medium energy heavy ion superconducting linac.

    SciTech Connect

    Ostroumov, P. N.; Kolomiets, A. A.; Kashinsky, D. A.; Minaev, S. A.; Pershin, V. I.; Tretyakova, T. E.; Yaramishev, S. G.; Physics; Inst. of Theoretical and Experimental Physics

    2002-06-01

    The nuclear science community considers the construction of the Rare Isotope Accelerator (RIA) facility as a top priority. The RIA includes a 1.4 GV superconducting linac for production of 400 kW cw heavy ion beams. The initial acceleration of heavy ions delivered from an electron cyclotron resonance ion source can be effectively performed by a 57.5 MHz 4-m long room temperature RFQ. The principal specifications of the RFQ are (i) formation of extremely low longitudinal emittance, (ii) stable operation over a wide range of voltage for acceleration of various ion species needed for RIA operation, and (iii) simultaneous acceleration of two-charge states of uranium ions. cw operation of an accelerating structure leads to a number of requirements for the resonators such as high shunt impedance, efficient water cooling of all parts of the resonant cavity, mechanical stability together with precise alignment, reliable rf contacts, a stable operating mode, and fine tuning of the resonant frequency during operation. To satisfy these requirements a new resonant structure has been developed. This paper discusses the beam dynamics and electrodynamics design of the RFQ cavity, as well as some aspects of the mechanical design of the low-frequency cw RFQ.

  11. Optimizing Frequency-Modulated CW EDMR in silicon

    NASA Astrophysics Data System (ADS)

    Zhu, Lihuang; van Schooten, Kipp; Ramanathan, Chandrasekhar

    Electrically detected magnetic resonance (EDMR) is a powerful method of probing dopant and defect spin states in semiconductor devices. Moreover, at the single dopant level, these spin states are heavily investigated as potential qubit systems, though facile electronic access to single dopants is exceedingly difficult. We therefore characterize detection sensitivities of frequency-modulated CW-EDMR of phosphorus donors in silicon Si:P using a home-built 2.5 GHz system (~80 mT) at 5 K. An arbitrary waveform generator controls the frequency modulation, allowing us to optimize the signal to noise ratio (SNR) of both the dangling bond and phosphorus donor signals against multiple experimental parameters, such as modulation amplitude and modulation frequency. The optimal range of frequency modulation parameters is constrained by the relaxation time of the phosphorous electron at 5 K, resulting in the same sensitivity limit as field modulated CW-EDMR, but offers some technical advantages; e.g. reducing the relative contribution of magnetic field induced currents and eliminating the need for field modulation coils. We further characterize the EDMR SNR in Si:P as a function of optical excitation energy by using a narrow line laser, tunable across donor exciton and band gap states.

  12. CW arc-lamp-pumped alexandrite lasers

    SciTech Connect

    Samelson, H.; Walling, J.C.; Wernikowski, T.; Harter, D.J.

    1988-06-01

    The performance characteristics of arc-lamp- (Xe and Hg) pumped, CW alexandrite lasers are described in detail. The modes of operation considered are free running, tuned, and repetitively Q-switched. The experimental arrangement and apparatus are also outlined. The experimental results are discussed in terms of a steady-state model, and the areas of agreement and difficulty are pointed out.

  13. Cw operation of the FMIT RFQ accelerator

    SciTech Connect

    Cornelius, W.D.

    1985-01-01

    Recently, we have achieved reliable cw operation of the Fusion Materials Irradiation Test (FMIT) radio-frequency quadrupole (RFQ) accelerator. In addition to the operational experiences in achieving this status, some of the modifications of the vacuum system, cooling system, and rf structure are discussed. Preliminary beam-characterization results are presented. 10 refs., 8 figs.

  14. A CW Gunn Diode Switching Element.

    ERIC Educational Resources Information Center

    Hurtado, Marco; Rosenbaum, Fred J.

    As part of a study of the application of communication satellites to educational development, certain technical aspects of such a system were examined. A current controlled bistable switching element using a CW Gunn diode is reported on here. With modest circuits switching rates of the order of 10 MHz have been obtained. Switching is initiated by…

  15. Design of 57.5 MHz cw RFQ structure for the rare isotope accelerator facility.

    SciTech Connect

    Ostroumov, P. N.; Kolomiets, A. A.; Kashinsky, D. A.; Minaev, S. A.; Pershin, V. I.; Yaramishev, S. G.; Tretyakova, T. E.

    2002-01-29

    The Rare Isotope Accelerator (RIA) facility includes a driver linac for production of 400 kW CW heavy-ion beams. The initial acceleration of heavy-ions delivered from an ECR ion source can be effectively performed by a 57.5 MHz four-meter long RFQ. The principal specifications of the RFQ are: (1) formation of extremely low longitudinal emittance; (2) stable operation over a wide range of voltage for acceleration of various ion species needed for RIA operation; (3) simultaneous acceleration of two-charge states of uranium ions. CW operation of an accelerating structure leads to a number of requirements for the resonators such as high shunt impedance, efficient water cooling of all parts of the resonant cavity, mechanical stability together with precise alignment, reliable rf contacts, a stable operating mode and fine tuning of the resonant frequency during operation. To satisfy these requirements a new resonant structure has been developed. This paper discusses beam dynamics and electrodynamics design of the RFQ cavity, as well as, some aspects of the mechanical design of this low-frequency CW RFQ.

  16. The 1.083 micron tunable CW semiconductor laser

    NASA Technical Reports Server (NTRS)

    Wang, C. S.; Chen, Jan-Shin; Lu, Ken-Gen; Ouyang, Keng

    1991-01-01

    A tunable CW laser is desired to produce light equivalent to the helium spectral line at 1.08 microns. This laser will serve as an optical pumping source for He-3 and He-4 atoms used in space magnetometers. This light source can be fabricated either as a semiconductor laser diode or a pumped solid state laser. Continuous output power of greater than 10 mW is desired. Semiconductor lasers can be thermally tuned, but must be capable of locking onto the helium resonance lines. Solid state lasers must have efficient pumping sources suitable for space configuration. Additional requirements are as follows: space magnetometer applications will include low mass (less than 0.5 kg), low power consumption (less than 0.75 W), and high stability/reliability for long missions (5-10 years).

  17. Parametric four-wave mixing using a single cw laser.

    PubMed

    Brekke, E; Alderson, L

    2013-06-15

    Four-wave mixing can be used to generate coherent output beams, with frequencies difficult to acquire in commercial lasers. Here, a single narrow external cavity diode laser locked to the two photon 5s-5d transition in rubidium is combined with a tapered amplifier system to produce a high power cw beam at 778 nm and used to generate coherent light at 420 nm through parametric four-wave mixing. This process is analyzed in terms of the intensity and frequency of the incoming beam as well as the atomic density of the sample. The efficiency of the process is currently limited when on resonance due to the absorption of the 420 nm beam, and modifications should allow a significant increase in output power. PMID:23939005

  18. Two-color resonance-enhanced multiphoton ionization study of the lowest Rydberg p state of bis(ɛ6-benzene)chromium and its deuterated derivatives

    NASA Astrophysics Data System (ADS)

    Ketkov, Sergey Yu.; Selzle, Heinrich L.; Schlag, Edward W.

    2004-07-01

    Two-color resonance-enhanced multiphoton ionization (REMPI) spectra of jet-cooled (η6-C6H6)2Cr(1), (η6-C6D6)2Cr(2), and (η6-C6D6)(η6-C6D5H)Cr(3) have been measured with use of the 3dz2→R4px,y Rydberg transition as the first step of the electronic excitation. The 000 Rydberg component shifts by 59 and 54 cm-1 to red when one goes from 1 to 2 and 3, respectively. Surprisingly, the REMPI spectra of 1-3 show very rich vibronic structures revealing both totally symmetric vibrations and degenerate vibrational modes. Presence of intense peaks corresponding to the e2g modes in the spectra of 1 and 2 is indicative of Jahn-Teller coupling in the R4px,y Rydberg state. Additional REMPI resonances appear on going from 1 and 2 to 3 as a result of the symmetry reduction. The vibronic components in the spectra of 1-3 were assigned on the basis of the selection rules and comparison with the vibrational frequencies of the 1 and 2 ground-state molecules. The frequencies of over 10 normal vibrations have been determined for the gas-phase 1-3 Rydberg-state molecules from the REMPI experiment. The wavenumber corresponding to the lowest-energy mode (the ring torsion vibration) appears to be 40 cm-1 in 1 and 35 cm-1 in the deuterated complexes. The REMPI peaks are homogeneously broadened. The lower lifetime limits for the upper-state components increase on going from the vibrationless level to higher-lying vibronic states and on going from 1 to the deuterated derivatives.

  19. Ionic rotational branching ratios in resonant enhanced multiphoton ionization of NO via the A2Sigma(+)(3s sigma) and D2Sigma(+)(3p sigma) states

    NASA Astrophysics Data System (ADS)

    Rudolph, H.; McKoy, V.; Dixit, S. N.; Huo, W. M.

    1988-01-01

    Results are presented for the rotationally resolved photoelectron spectra resulting from a (2 + 1) one-color resonant enhanced multiphoton ionization (REMPI) of NO via the rotationally clean S21(11.5) and mixed S11(15.5) + R21(15.5) branches of the 0-0 transition in the D-X band. The calculations were done in the fixed-nuclei frozen core approximation. The resulting photoionization spectra, convoluted with a Lorentzian detection function, agree qualitatively with experimental results of Viswanathan et al. (1986) and support their conclusion that the nonspherical nature of the molecular potential creates a substantial l-mixing in the continuum, which in turn leads to the intense Delta N = 0 peak. The rather strong photoelectron energy dependence of the rotational branching ratios of the D 2Sigma(+) S21(11.5) line was investigated and compared to the weak energy dependence of the A 2Sigma(+) R22(21.5) line.

  20. Novel glutathione conjugates of phenyl isocyanate identified by ultra-performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance.

    PubMed

    Johansson Mali'n, Tove; Lindberg, Sandra; Åstot, Crister

    2014-01-01

    Phenyl isocyanate is a highly reactive compound that is used as a reagent in organic synthesis and in the production of polyurethanes. The potential for extensive occupational exposure to this compound makes it important to elucidate its reactivity towards different nucleophiles and potential targets in the body. In vitro reactions between glutathione and phenyl isocyanate were studied. Three adducts of glutathione with phenyl isocyanate were identified using ultra-performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance (NMR). Mass spectrometric data for these adducts have not previously been reported. Nucleophilic attack on phenyl isocyanate occurred via either the cysteinyl thiol group or the glutamic acid α-amino group of glutathione. In addition, a double adduct was formed by the reaction of both these moieties. NMR analysis confirmed the proposed structure of the double adduct, which has not previously been described. These results suggest that phenyl isocyanate may react with free cysteines, the α-amino group and also with lysine residues whose side chain contains a primary amine.

  1. Biomarkers probed in saliva by surface plasmon resonance imaging coupled to matrix-assisted laser desorption/ionization mass spectrometry in array format.

    PubMed

    Musso, Johana; Buchmann, William; Gonnet, Florence; Jarroux, Nathalie; Bellon, Sophie; Frydman, Chiraz; Brunet, Didier-Luc; Daniel, Regis

    2015-02-01

    Detection of protein biomarkers is of major interest in proteomics. This work reports the analysis of protein biomarkers directly from a biological fluid, human saliva, by surface plasmon resonance imaging coupled to mass spectrometry (SPRi-MS), using a functionalized biochip in an array format enabling multiplex SPR-MS analysis. The SPR biochip presented a gold surface functionalized by a self-assembled monolayer of short poly(ethylene oxide) chains carrying an N-hydroxysuccinimide end-group for the immobilization of antibodies. The experiments were accomplished without any sample pre-purification or spiking with the targeted biomarkers. SPRi monitoring of the interactions, immune capture from the biochip surface, and finally on-chip matrix-assisted laser desorption/ionization-MS structural identification of two protein biomarkers, salivary α-amylase and lysozyme, were successively achieved directly from saliva at the femtomole level. For lysozyme, the on-chip MS identification was completed by a proteomic analysis based on an on-chip proteolysis procedure and a peptide mass fingerprint. PMID:25524230

  2. Dithranol as a matrix for matrix assisted laser desorption/ionization imaging on a fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Le, Cuong H; Han, Jun; Borchers, Christoph H

    2013-11-26

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided.

  3. High resolution UV resonance enhanced two-photon ionization spectroscopy with mass selection of biologically relevant molecules in the gas phase

    NASA Astrophysics Data System (ADS)

    Chervenkov, S.; Wang, P. Q.; Karaminkov, R.; Chakraborty, T.; Braun, Juergen E.; Neusser, Hans J.

    2005-04-01

    The high resolution Doppler-free resonance-enhanced two-photon ionization (R2PI) spectroscopy with mass selection of jet-cooled (2-12 K) molecular species is a powerful experimental method providing comprehensive information on both isolated molecules and molecular clusters. We have demonstrated for the first time that this technique can be applied to large molecules and provides detailed information on their conformational structure. It allows rotationally resolved (FWHM = 70 MHz) spectra of the vibronic bands of the S1<--S0 electronic transition of the studied molecular systems to be measured. A specially designed computer-assisted fitting routine based on genetic algorithms is used to determine their rotational constants in the ground and excited electronic states, respectively, and the transition moment ratio. To interpret the experimental information and to discriminate and unambiguously assign the observed approach to the study of the neurotransmitter molecule, ephedrine. The results elucidate the role of the intramolecular hydrogen bonds stabilizing the respective conformations and affecting their intrinsic properties.

  4. Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Le, Cuong H.; Han, Jun; Borchers, Christoph H.

    2013-01-01

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided. PMID:24300588

  5. A 1 + 1' resonance-enhanced multiphoton ionization scheme for rotationally state-selective detection of formaldehyde via the à (1)A2 ← X[combining tilde] (1)A1 transition.

    PubMed

    Park, G Barratt; Krüger, Bastian C; Meyer, Sven; Wodtke, Alec M; Schäfer, Tim

    2016-08-10

    The formaldehyde molecule is an important model system for understanding dynamical processes in small polyatomic molecules. However, prior to this work, there have been no reports of a resonance-enhanced multiphoton ionization (REMPI) detection scheme for formaldehyde suitable for rovibrationally state-selective detection in molecular beam scattering experiments. Previously reported tunable REMPI schemes are either non-rotationally resolved, involve multiple resonant steps, or involve many-photon ionization steps. In the current work, we present a new 1 + 1' REMPI scheme for formaldehyde. The first photon is tunable and provides rotational resolution via the vibronically allowed à (1)A2 ← X[combining tilde] (1)A1 transition. Molecules are then directly ionized from the à state by one photon of 157 nm. The results indicate that the ionization cross section from the 4(1) vibrational level of the à state is independent of the rotational level used as intermediate, to within experimental uncertainty. The 1 + 1' REMPI intensities are therefore directly proportional to the à ← X[combining tilde] absorption intensities and can be used for quantitative measurement of X[combining tilde]-state population distributions.

  6. A 100 MV cryomodule for CW operation

    SciTech Connect

    Charles Reece

    2005-07-10

    A cryomodule designed for high-gradient CW operation has been built at Jefferson Lab. The Renascence cryomodule is the final prototype of a design for use in the 12 GeV CEBAF upgrade. The module uses eight 7-cell 1497 MHz cavities to be individually powered by 13 kW klystrons. Specifications call for providing >109 MV CW with < 250 W of dynamic heat at 2.07 K. The module incorporates a new generation of tuners and higher power input waveguides. A mixture of the new HG and LL cavity shapes are used. A new high thermal conductivity RF feedthrough has been developed and used on the 32 HOM coupler probes of Renascence. The cryomodule assembly is complete. Testing is to begin late June. Design features and initial test data will be presented.

  7. Characterization of IRDye 800CW chlorotoxin as a targeting agent for brain tumors.

    PubMed

    Kovar, Joy L; Curtis, Evan; Othman, Shadi F; Simpson, Melanie A; Olive, D Michael

    2013-09-15

    Primary brain tumors present significant challenges for surgical resection because of their location and the frequent occurrence of malignant projections extending beyond the primary tumor. Visualization of the tumor margins during surgery is critical for a favorable outcome. We report the use of IRDye 800CW chlorotoxin (CLTX) as a targeted imaging agent for brain tumors in a spontaneous mouse model of medulloblastoma, ND2:SmoA1. Specificity and functionality of the targeted agent were confirmed in cell-based assays. Tumors were detected by magnetic resonance imaging and IRDye 800CW CLTX administered to individual animals for optical imaging at 1-month increments. The integrity of the blood-brain barrier (BBB) was measured by Evan's Blue perfusion prior to sacrifice. Results show that IRDye 800CW CLTX specifically targeted tumor tissue. The extravasation of Evan's Blue was observed in all tumors, suggesting that the presence of the tumors can introduce alterations in the permeability of the BBB. Because increased vascular permeability was observed early in the disease model, larger dye-labeled imaging agents that exceed current BBB size restrictions may warrant renewed consideration as candidates for tumor detection and surgical resection. Our study provides data characterizing in vitro and in vivo use of IRDye 800CW CLTX as a broadly applicable tumor imaging agent. PMID:23711726

  8. Characterization of IRDye 800CW chlorotoxin as a targeting agent for brain tumors.

    PubMed

    Kovar, Joy L; Curtis, Evan; Othman, Shadi F; Simpson, Melanie A; Olive, D Michael

    2013-09-15

    Primary brain tumors present significant challenges for surgical resection because of their location and the frequent occurrence of malignant projections extending beyond the primary tumor. Visualization of the tumor margins during surgery is critical for a favorable outcome. We report the use of IRDye 800CW chlorotoxin (CLTX) as a targeted imaging agent for brain tumors in a spontaneous mouse model of medulloblastoma, ND2:SmoA1. Specificity and functionality of the targeted agent were confirmed in cell-based assays. Tumors were detected by magnetic resonance imaging and IRDye 800CW CLTX administered to individual animals for optical imaging at 1-month increments. The integrity of the blood-brain barrier (BBB) was measured by Evan's Blue perfusion prior to sacrifice. Results show that IRDye 800CW CLTX specifically targeted tumor tissue. The extravasation of Evan's Blue was observed in all tumors, suggesting that the presence of the tumors can introduce alterations in the permeability of the BBB. Because increased vascular permeability was observed early in the disease model, larger dye-labeled imaging agents that exceed current BBB size restrictions may warrant renewed consideration as candidates for tumor detection and surgical resection. Our study provides data characterizing in vitro and in vivo use of IRDye 800CW CLTX as a broadly applicable tumor imaging agent.

  9. Energy saver prototype accelerating resonator

    SciTech Connect

    Kerns, Q.; May, M.; Miller, H.W.; Reid, J.; Turkot, F.; Webber, R.; Wildman, D.

    1981-06-01

    A fixed frequency rf accelerating resonator has been built and tested for the Fermilab Energy Saver. The design parameters and prototype resonator test results are given. The resonator features a high permeability nickel alloy resistor which damps unwanted modes and corona rolls designed with the aid of the computer code SUPERFISH. In bench measurements, the prototype resonator has achieved peak accelerating voltages of 500 kV for a 1% duty cycle and cw operation at 360 kV. 4 refs.

  10. Dual electrospray ionization source for confident generation of accurate mass tags using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Nepomuceno, Angelito I; Muddiman, David C; Bergen, H Robert; Craighead, James R; Burke, Michael J; Caskey, Patrick E; Allan, Jonathan A

    2003-07-15

    Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has rapidly established a prominent role in proteomics because of its unparalleled resolving power, sensitivity and ability to achieve high mass measurement accuracy (MMA) simultaneously. However, space-charge effects must be quantitatively, routinely, and confidently corrected because they are known to profoundly influence MMA. We argue that the most effective way to account for space-charge effects is to introduce an internal mass calibrant (IMC) using a dual electrospray ionization (ESI) source where the IMC is added from a separate ESI emitter. The major disadvantage of our initial dual ESI source to achieve high MMA, and arguably the only one, was the time required to switch between the analyte emitter and IMC emitter (i.e., >300 ms). While this "switching time" was acceptable for direct infusion experiments, it did not lend itself to high-throughput applications or when conducting on-line liquid separations. In this report, we completely redesigned the dual ESI source and demonstrate several key attributes. First, the new design allows for facile alignment of ESI emitters, undetectable vibration, and the ability to extend to multiple emitters. Second, the switching time was reduced to <50 ms, which allowed the analyte and IMC to be accumulated "simultaneously" in the external ion reservoir and injected as a single ion packet into the ion cyclotron resonance cell, eliminating the need for a separate accumulation and ion injection event for the IMC. Third, by using a high concentration of the IMC, the residence time on this emitter could be reduced to approximately 80 ms, allowing for more time spent accumulating analyte ions of significantly lower concentration. Fourth, multiplexed on-line separations can be carried out providing increased throughput. Specifically, the new dual ESI source has demonstrated its ability to produce a stable ion current over a 45-min time period at 7 T

  11. Molecular characterisation of soil organic matter by laser-desorption ionization Fourier-transform ion cyclotron resonance mass spectrometry (LDI-FT-ICR-MS)

    NASA Astrophysics Data System (ADS)

    Abiven, S.; Fuchser, J.; Schmidt, M. W. I.; Dittmar, T.

    2012-04-01

    Soil organic matter (SOM) characterisation has been an analytical challenge for decades. On one hand, methods like humic substances extraction describe large pools of molecules, but these extractions target operationnally- rather than chemically-defined pools. On the other hand, specific compound analysis provides a more precise overview on the molecules present in the soil, but the sum of these molecules represents only a minor portion of the soil organic matter. Despite these shortcomings, soil organic matter characterisation is used in many concepts of soil science. For example, the soil aggregation hierarchical model describes the physical organisation of soils into fractions bound together by organic matter of different quality for each size fraction. Due to the method inadequation, most of these concepts still need to be validated. We took advantage of a unique analytical set-up coupling laser-desorption ionization (LDI) to ultrahigh-resolution mass spectrometry via the Fourier-transform ion cyclotron resonance technique (FT-ICR-MS) to further characterise soil organic matter and to validate the soil aggregation hierarchical model. Soil aggregates (3-5 mm) were collected from two soils, a cambisol (32 % clay, 4.2 %C), and a loess-derived soil (15% clay, 1.6 %C). Aggregates were fractionated by fast wetting into <63, 63-125, 125-250 and > 250 μm fractions. These fractions were air-dried and ground to powder prior to analysis. LDI-FT-ICR-MS analyses were performed on otherwise untreated samples. Thousands of molecular formulae were identified in each samples, many of them could be associated with polyphenolic structures. The combination of LDI with ultrahigh-resolution FT-ICR-MS offers fundmentally new insights into soil organic matter, one of the largest organic matter pools on Earth.

  12. Double-arm three-dimensional ion imaging apparatus for the study of ion pair channels in resonance enhanced multiphoton ionization.

    PubMed

    Poretskiy, M S; Chichinin, A I; Maul, C; Gericke, K-H

    2016-02-01

    We present a novel experimental configuration for the full quantitative characterization of the multichannel resonance enhanced multiphoton ionization (REMPI) of small molecules in cases when the ion-pair dissociation channel is important. For this purpose, a double-arm time-of-flight mass spectrometer with three-dimensional (3D) ion imaging detectors at both arms is constructed. The REMPI of HCl molecules is used to examine the constructed setup. The apparatus allows us to perform simultaneous measurements of the 3D velocity vector distributions of positive (H(+), HCl(+), and Cl(+)) and negative (Cl(-)) photoions. The characterization consists of the determination of "two-photon absorption cross sections" for the process HCl(X)+2hν → HCl*, one-photon absorption cross sections for subsequent processes HCl* + hν → HCl*, and the probability of the subsequent non-adiabatic transition HCl* → HCl(B) → H(+) + Cl(-), which leads to ionic pairs. All these data should be obtained from the analysis of the dependencies of the number of ions on the laser energy. The full characterization of the laser beam and the knowledge of the ion detection probability are necessary parts of the analysis. Detailed knowledge of losses of produced ions in the mass spectrometer before detection requires understanding and characterization of such processes like electron emission from metallic grids under ion bombardment or charge transfer between positive ions and the metal surface of the grids, like Cl(+) + (grid) → Cl(-). These important phenomena from surface science are rarely discussed in the imaging literature, and here, we try to compensate for this shortcoming. PMID:26931834

  13. Analysis of the (1)A' S1 ← (1)A' S0 and (2)A' D0 ← (1)A' S1 band systems in 1,2-dichloro-4-fluorobenzene by means of resonance-enhanced-multi-photon-ionization (REMPI) and mass-analyzed-threshold-ionization (MATI) spectroscopy.

    PubMed

    Krüger, Sascha; Grotemeyer, Jürgen

    2016-03-14

    Resonance enhanced multiphoton ionization (REMPI) and mass analyzed threshold ionization (MATI) spectroscopy have been applied in order to investigate the vibrational structure of 1,2-dichloro-4-fluorobenzene (1,2,4-DCFB) in its first excited state (S1) and the cationic ground state (D0). The selection of the state prior to ionization resulted in MATI spectra with different intensity distributions thus giving access to many vibrational levels. To support the experimental findings, geometry optimizations and frequency analyses at DFT (density functional) and TDDFT (time-dependent density functional) levels of theory have been applied. Additionally, a multidimensional Franck-Condon approach has been used to calculate the vibrational intensities from the DFT calculations. An excellent agreement between simulated and measured REMPI and MATI spectra allowed for a confident assignment of vibrational levels and mechanisms active during excitation and ionization. In order to avoid any ambiguity regarding the assignment of the vibrational bands to normal modes, Duschinsky normal mode analysis has been performed to correlate the ground state (S0) normal modes of 1,2,4-DCFB with the benzene derived Wilson nomenclature. From the REMPI spectra the electronic excitation energy (EE) of 1,2-dichloro-4-fluorobenzene could be determined to be 35 714 ± 2 cm(-1) while the MATI spectra yielded the adiabatic ionization energy (IE) of 1,2-dichloro-4-fluorobenzene which could be determined to be 73 332 ± 7 cm(-1).

  14. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    SciTech Connect

    Mezhenin, A V; Azyazov, V N

    2012-12-31

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio {Pi}. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at {tau}{sub d} {<=} 7. Efficient energy extraction from the OIL active medium is achieved in the case of {tau}{sub d} = 5 - 7, {Pi} = 4 - 8. (lasers)

  15. CW single transverse mode all-fiber Tm3+-doped silica fiber laser

    NASA Astrophysics Data System (ADS)

    Song, E. Z.; Li, W. H.; You, L.

    2012-04-01

    The CW 25.6 W output power with a slope efficiency of 30.6% respected to the pump power from a CW single transverse mode all-fiber Tm3+-doped Silica Fiber Laser is reported. The all-fiber laser is made up by progressively splicing the pigtail fiber, matched FBG fiber and Tm fiber. The reflective FBG and Tm3+-doped fiber end Fresnel reflection build up the laser resonance cavity. Due to the multi-mode FBG as the reflective mirror, the output laser spectrum is multi-peaks at high output power, but the spectrum width is less than 2 nm at 1.94 μm. We estimate the beam quality to be M 2 = 2.39, clearly indicating nearly diffraction-limited beam propagation.

  16. Tissue imaging and serum lipidomic profiling for screening potential biomarkers of thyroid tumors by matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Guo, Shuai; Qiu, Ling; Wang, Yanming; Qin, Xuzhen; Liu, Hui; He, Manwen; Zhang, Yaping; Li, Zhili; Chen, Xiaohong

    2014-07-01

    Changes in serum lipidome and in tissue lipidome are associated with cancer. In this study, tissue mass spectrometry imaging (MSI) and serum lipid profiling by matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) were performed to investigate significantly changed lipids in both tumor (malignant thyroid cancer (MTC) and benign thyroid tumor (BTT)) tissues and sera. Y-scatterplots of variable importance in the projection (VIP) values vs. fold change values indicate that change trends in the levels of ten lipids (i.e., phosphatidylcholine (PC)(34:1), PC(36:1), PC(38:6), phosphatidic acid (PA) (36:2), PA(36:3), PA(38:3), PA(38:4), PA(38:5), PA(40:5), and sphingomyelin (SM)(34:1)) in both tissues and sera from MTC patients, BTT patients, and normal individuals are significantly associated with these three types of pathophysiological status. In order to examine their diagnostic ability, 289 serum samples from 124 MTC patients, 43 BTT patients, and 122 normal controls were randomly divided into the training set and validation set. A biomarker of PC(34:1) exhibited excellent diagnostic ability to differentiate both MTC and BTT patients from normal individuals, with an area under the receiver operating characteristic (ROC) curve value of 0.984, a sensitivity of 96.4 %, and a specificity of 92.7 %. A panel which included PA(36:3) and SM(34:1) could distinguish between MTC and BTT, with an area under receiver operating characteristic curve (AUC) of 0.961, a sensitivity of 87.8 %, and a specificity of 92.9 %. It is worth noting that a panel consisting of PC(34:1), PA(36:3), and SM(34:1) could differentiate MTC patients from both BTT patients and normal individuals, with an AUC of 0.841, a sensitivity of 86.6 %, and a specificity of 75.5 %.

  17. Preliminary fingerprinting of Athabasca oil sands polar organics in environmental samples using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Headley, J V; Barrow, M P; Peru, K M; Fahlman, B; Frank, R A; Bickerton, G; McMaster, M E; Parrott, J; Hewitt, L M

    2011-07-15

    There is a growing need to develop analytical methods that can distinguish compounds found within industrially derived oil sands process water (OSPW) from those derived from natural weathering of oil sands deposits. This is a difficult challenge as possible leakage beyond tailings pond containments will probably be in the form of mixtures of water-soluble organics that may be similar to those leaching naturally into aquatic environments. We have evaluated the potential of negative ion electrospray ionization high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) for comparing oil sands polar organics from tailing ponds, interceptor wells, groundwater, river and lake surface waters. Principal component analysis was performed for all species observed. which included the O(2) class (often assumed to be monocarbxoylic naphthenic acids) along with a wide range of other species including humic substances in the river and lake samples: O(n) where n=1-16; NO(n) and N(2)O(n) where n=1-13; and O(n)S and O(n)S(2) where n=1-10 and 1-8, respectively. A broad range of species was investigated because classical naphthenic acids can be a small fraction of the 'organics' detected in the polar fraction of OSPW, river water and groundwater. Aquatic toxicity and environmental chemistry are attributed to the total organics (not only the classical naphthenic acids). The distributions of the oil sands polar organics, particularly the sulfur-containing species, O(n)S and O(n)S(2), may have potential for distinguishing sources of OSPW. The ratios of species containing O(n) along with nitrogen-containing species: NO(n), and N(2)O(n), were useful for differentiating organic components derived from OSPW from those found in river and lake waters. Further application of the FTICRMS technique for a diverse range of OSPW of varying ages and composition, as well as the surrounding groundwater wells, may be critical in assessing whether leakage from industrial sources

  18. Detection of Biosignatures using Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Implications for the Search for Life in the Solar System

    NASA Astrophysics Data System (ADS)

    Richardson, C. D.; Kotler, J. M.; Hinman, N. W.; Scott, J. R.

    2008-12-01

    Detection of bio/organic signatures, defined as an organic structure produced by living organisms or derived from other biogenic organic compounds, is essential to investigating the origin and distribution of extant or extinct life in the solar system. In conjunction with mineralogical, inorganic, and isotopic data, the detection and identification of bio/organic signatures can assist in linking biochemical and geochemical processes. Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a proven method of obtaining bio/organic signatures from a range of geological materials. Sulfate salts were studied because they are found on Mars and Jovian satellites. The goal here was to determine (1) which combinations of bio/organic compounds and sulfate salts produced distinctive spectral signatures, and (2) the detection limit of the method. In these experiments, thenardite (Na2SO4) was mixed with stearic acid to determine the detection limit of GALDI-FTICR-MS, previously estimated to be 3 ppt, which corresponds to approximately 7 zeptomoles (10-21) per laser shot. All spectra were collected with little to no sample preparation and were acquired using a single laser shot. Unlike conventional analytical practices, the signal-to-noise ratio increased as the concentration of bio/organic compounds decreased relative to the mineral host. In combination with thenardite, aromatic amino acids were observed to undergo simple cation attachment ([M+Na]+) due to the π-bonded aromatic ring. Subsequent cation substitution of the carboxyl group led to formation of peaks representing double cation attachment ([M-H+Na]Na+). Spectra from naturally occurring thenardite and jarosite (XFe3(OH)6(SO4)2) revealed the presence of high mass cluster ions; analysis of their isotopic distribution suggested the presence of bio/organic compounds. High mass cluster ions, both organic and inorganic, readily

  19. Ring-Down Spectroscopy for Characterizing a CW Raman Laser

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

    2007-01-01

    .A relatively simple technique for characterizing an all-resonant intracavity continuous-wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, characterizing signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes. Heretofore, in order to characterize resonant-cavity-based Raman lasers, it has usually been necessary to manipulate the frequencies and power levels of pump lasers and, in each case, to take several sets of measurements. In cases involving ultra-high-Q resonators, it also has been desirable to lock pump lasers to resonator modes to ensure the quality of measurement data. Simpler techniques could be useful. In the present ring-down spectroscopic technique, one infers the parameters of interest from the decay of the laser out of its steady state. This technique does not require changing the power or frequency of the pump laser or locking the pump laser to the resonator mode. The technique is based on a theoretical analysis of what happens when the pump laser is abruptly switched off after the Raman generation reaches the steady state. The analysis starts with differential equations for the evolution of the amplitudes of the pump and Stokes electric fields, leading to solutions for the power levels of the pump and Stokes fields as functions of time and of the aforementioned parameters. Among other things, these solutions show how the ring-down time depends, to some extent, on the electromagnetic energy accumulated in the cavity. The solutions are readily converted to relatively simple equations for the parameters as functions of quantities that can be determined from measurements of the time-dependent power levels. For example, the steady-state intracavity conversion efficiency is given by G1/G2 1 and the threshold power is given by Pin(G2/G1)2, where Pin is the steady-state input pump power immediately prior to

  20. Resonance multiphoton ionization and dissociation of dimethyl ether via the {\\skew1\\tilde{\\rm C}^{\\prime}}, {\\skew1\\tilde{\\rm C}} and \\tilde{\\rm B} states

    NASA Astrophysics Data System (ADS)

    Mejia-Ospino, E.; García, G.; Guerrero, A.; Alvarez, I.; Cisneros, C.

    2005-01-01

    The three-photon resonance four-photon ionization and dissociation spectra of dimethyl ether (DME) are presented in the wavelength range 450-550 nm at 1 nm intervals. The (3+1) REMPI spectra show three prominent bands corresponding to the \\tildeB \\leftarrow \\skew1\\tildeX, {\\skew1\\tildeC} \\leftarrow \\skew1\\tildeX and {\\skew1\\tildeC^{\\prime}} \\leftarrow \\skew1\\tildeX transitions with origins at 61 457 cm-1 (7.615 eV), 59 055 cm-1 (7.322 eV) and 58 010 cm-1 (7.194 eV), respectively. Several ionized species, CH3+, CHnO+ (n = 1-3) and CH3OCH3+, are observed in the region of wavelengths studied here. In order to compare the results, a shorter wavelength multiphoton dissociation and ionization of DME at 355 nm is also presented. At this wavelength, DME undergoes neutral dissociation to CH3 and CH3O and each fragment is then ionized by multiphoton absorption. The fragmentation at 355 nm is very intense and only small fragments such as CH3+, CHO+, CH2+, CH+ and C+ ions are observed. The measurement of photoelectron energy allows us to establish that the DME ionization potential is at least 9.55 ± 0.15 eV. The experiments were performed using a Nd:YAG-OPO (optical parametric oscillator) tunable laser system coupled to a time-of-flight mass spectrometer and a hemispherical electron energy analyser.

  1. Ionization of polarized hydrogen atoms

    SciTech Connect

    Alessi, J.G.

    1983-01-01

    Methods are discussed for the production of polarized H/sup -/ ions from polarized atoms produced in ground state atomic beam sources. Present day sources use ionizers of two basic types - electron ionizers for H/sup +/ Vector production followed by double charge exchange in a vapor, or direct H/sup -/ Vector production by charge exchange of H/sup 0/ with Cs/sup 0/. Both methods have ionization efficiencies of less than 0.5%. Ionization efficiencies in excess of 10% may be obtained in the future by the use of a plasma ionizer plus charge exchange in Cs or Sr vapor, or ionization by resonant charge exchange with a self-extracted D/sup -/ beam from a ring magnetron or HCD source. 36 references, 4 figures.

  2. Moderate-power cw fibre lasers

    SciTech Connect

    Kurkov, Andrei S; Dianov, Evgenii M

    2004-10-31

    A review of the development and investigation of moderate-power (10{sup -1}-10{sup 2} W) cw fibre lasers is presented. The properties of optical fibres doped with rare-earth ions and methods for fabricating double-clad fibres are considered. The methods for fabrication of fibre Bragg gratings used as selective reflectors are discussed and the grating properties are analysed. The main pump schemes for double-clad fibre lasers are described. The properties of fibre lasers doped with neodymium, ytterbium, erbium, thulium, and holmium ions are also considered. The principles of fabrication of Raman converters of laser radiation based on optical fibres of different compositions are discussed and the main results of their studies are presented. It is concluded that fibre lasers described in the review can produce moderate-power radiation at any wavelength in the spectral range from 0.9 to 2 {mu}m. (review)

  3. Structure and Function of CW Domain Containing Proteins.

    PubMed

    Liu, Yanli; Liu, Shasha; Zhang, Xinxin; Liang, Xiao; Zahid, Kashif Rafiq; Liu, Ke; Liu, Jinlin; Deng, Lingfu; Yang, Jihong; Qi, Chao

    2016-01-01

    The CW domain is a zinc binding domain, composed of approximately 50- 60 amino acid residues with four conserved cysteine (C) and two to four conserved tryptophan (W) residues. The members of the superfamily of CW domain containing proteins, comprised of 12 different eukaryotic nuclear protein families, are extensively expressed in vertebrates, vertebrate-infecting parasites and higher plants, where they are often involved in chromatin remodeling, methylation recognition, epigenetic regulation and early embryonic development. Since the first CW domain structure was determined 5 years ago, structures of five CW domains have been solved so far. In this review, we will discuss these recent advances in understanding the identification, definition, structure, and functions of the CW domain containing proteins. PMID:26806410

  4. Sequence analysis of the novel HLA-Cw*08 variant allele, Cw*0820, in a Chinese Han individual.

    PubMed

    Deng, Z-H; Xu, Y-P; Wang, D-M

    2009-09-01

    A novel human leukocyte antigen (HLA) allele, HLA-Cw*0820, was identified in a Chinese Han individual. It differs from the closest allele Cw*080101 by single nucleotide change at genomic nucleotide (nt) 1615 G>A (coding sequence nt 652 G>A, codon 194 GTC>ATC) in exon 4, which results in an amino acid change Val194Ile.

  5. Hyphenation of Thermal Analysis to Ultrahigh-Resolution Mass Spectrometry (Fourier Transform Ion Cyclotron Resonance Mass Spectrometry) Using Atmospheric Pressure Chemical Ionization For Studying Composition and Thermal Degradation of Complex Materials.

    PubMed

    Rüger, Christopher P; Miersch, Toni; Schwemer, Theo; Sklorz, Martin; Zimmermann, Ralf

    2015-07-01

    In this study, the hyphenation of a thermobalance to an ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometer (UHR FTICR MS) is presented. Atmospheric pressure chemical ionization (APCI) is used for efficient ionization. The evolved gas analysis (EGA), using high-resolution mass spectrometry allows the time-resolved molecular characterization of thermally induced processes in complex materials or mixtures, such as biomass or crude oil. The most crucial part of the setup is the hyphenation between the thermobalance and the APCI source. Evolved gases are forced to enter the atmospheric pressure ionization interface of the MS by applying a slight overpressure at the thermobalance side of the hyphenation. Using the FTICR exact mass data, detailed chemical information is gained by calculation of elemental compositions from the organic species, enabling a time and temperature resolved, highly selective detection of the evolved species. An additional selectivity is gained by the APCI ionization, which is particularly sensitive toward polar compounds. This selectivity on the one hand misses bulk components of petroleum samples such as alkanes and does not deliver a comprehensive view but on the other hand focuses particularly on typical evolved components from biomass samples. As proof of principle, the thermal behavior of different fossil fuels: heavy fuel oil, light fuel oil, and a crude oil, and different lignocellulosic biomass, namely, beech, birch, spruce, ash, oak, and pine as well as commercial available softwood and birch-bark pellets were investigated. The results clearly show the capability to distinguish between certain wood types through their molecular patterns and compound classes. Additionally, typical literature known pyrolysis biomass marker were confirmed by their elemental composition, such as coniferyl aldehyde (C10H10O3), sinapyl aldehyde (C11H12O4), retene (C18H18), and abietic acid (C20H30O2). PMID:26024433

  6. Hyphenation of Thermal Analysis to Ultrahigh-Resolution Mass Spectrometry (Fourier Transform Ion Cyclotron Resonance Mass Spectrometry) Using Atmospheric Pressure Chemical Ionization For Studying Composition and Thermal Degradation of Complex Materials.

    PubMed

    Rüger, Christopher P; Miersch, Toni; Schwemer, Theo; Sklorz, Martin; Zimmermann, Ralf

    2015-07-01

    In this study, the hyphenation of a thermobalance to an ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometer (UHR FTICR MS) is presented. Atmospheric pressure chemical ionization (APCI) is used for efficient ionization. The evolved gas analysis (EGA), using high-resolution mass spectrometry allows the time-resolved molecular characterization of thermally induced processes in complex materials or mixtures, such as biomass or crude oil. The most crucial part of the setup is the hyphenation between the thermobalance and the APCI source. Evolved gases are forced to enter the atmospheric pressure ionization interface of the MS by applying a slight overpressure at the thermobalance side of the hyphenation. Using the FTICR exact mass data, detailed chemical information is gained by calculation of elemental compositions from the organic species, enabling a time and temperature resolved, highly selective detection of the evolved species. An additional selectivity is gained by the APCI ionization, which is particularly sensitive toward polar compounds. This selectivity on the one hand misses bulk components of petroleum samples such as alkanes and does not deliver a comprehensive view but on the other hand focuses particularly on typical evolved components from biomass samples. As proof of principle, the thermal behavior of different fossil fuels: heavy fuel oil, light fuel oil, and a crude oil, and different lignocellulosic biomass, namely, beech, birch, spruce, ash, oak, and pine as well as commercial available softwood and birch-bark pellets were investigated. The results clearly show the capability to distinguish between certain wood types through their molecular patterns and compound classes. Additionally, typical literature known pyrolysis biomass marker were confirmed by their elemental composition, such as coniferyl aldehyde (C10H10O3), sinapyl aldehyde (C11H12O4), retene (C18H18), and abietic acid (C20H30O2).

  7. Four-channel surface coil array for sequential CW-EPR image acquisition.

    PubMed

    Enomoto, Ayano; Emoto, Miho; Fujii, Hirotada; Hirata, Hiroshi

    2013-09-01

    This article describes a four-channel surface coil array to increase the area of visualization for continuous-wave electron paramagnetic resonance (CW-EPR) imaging. A 776-MHz surface coil array was constructed with four independent surface coil resonators and three kinds of switches. Control circuits for switching the resonators were also built to sequentially perform EPR image acquisition for each resonator. The resonance frequencies of the resonators were shifted using PIN diode switches to decouple the inductively coupled coils. To investigate the area of visualization with the surface coil array, three-dimensional EPR imaging was performed using a glass cell phantom filled with a solution of nitroxyl radicals. The area of visualization obtained with the surface coil array was increased approximately 3.5-fold in comparison to that with a single surface coil resonator. Furthermore, to demonstrate the applicability of this surface coil array to animal imaging, three-dimensional EPR imaging was performed in a living mouse with an exogenously injected nitroxyl radical imaging agent. PMID:23832070

  8. Synthesis, in vitro evaluation, and in vivo metabolism of fluor/quencher compounds containing IRDye 800CW and Black Hole Quencher-3 (BHQ-3).

    PubMed

    Linder, Karen E; Metcalfe, Edmund; Nanjappan, Palaniappa; Arunachalam, Thangavel; Ramos, Kimberly; Skedzielewski, Tina Marie; Marinelli, Edmund R; Tweedle, Michael F; Nunn, Adrian D; Swenson, Rolf E

    2011-07-20

    Protease-cleavable peptides containing a suitable fluor/quencher (Fl/Q) pair are optically dark until cleaved by their target protease, generating fluorescence. This approach has been used with many Fl/Q pairs, but little has been reported with IRDye 800CW, a popular near-infrared (NIR) fluor. We explored the use of the azo-bond-containing Black Hole Quencher 3 (BHQ-3) as a quencher for IRDye 800CW and found that IRDye 800CW/BHQ-3 is a suitable Fl/Q pair, despite the lack of proper spectral overlap for fluorescence resonance energy transfer (FRET) applications. Cleavage of IRDye 800CW-PLGLK(BHQ-3)AR-NH(2) (8) and its D-arginine (Darg) analogue (9) by matrix metalloproteinases (MMPs) in vitro yielded the expected cleavage fragments. In vivo, extensive metabolism was found. Significant decomposition of a "non-cleavable" control IRDye 800CW-(1,13-diamino-4,7,10-trioxatridecane)-BHQ-3 (10) was evident in plasma of normal mice by 3 min post injection. The major metabolite showed a m/z and UV/vis spectrum consistent with azo bond cleavage in the BHQ-3 moiety. Preparation of an authentic standard of this metabolite (11) confirmed the assignment. Although the IRDye 800CW/BHQ-3 constructs showed efficient contact quenching prior to enzymatic cleavage, BHQ-3 should be used with caution in vivo, due to instability of its azo bond.

  9. Epicyclic Twin-Helix Ionization Cooling Simulations

    SciTech Connect

    Vasiliy Morozov, Yaroslav Derbenev, A. Afanaciev, R.P. Johnson

    2011-04-01

    Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a highluminosity muon collider. For the implementation of PIC, we earlier developed an epicyclic twin-helix channel with correlated behavior of the horizontal and vertical betatron motions and dispersion. We now insert absorber plates with short energy-recovering units located next to them at the appropriate locations in the twin-helix channel. We first demonstrate conventional ionization cooling in such a system with the optics uncorrelated. We then adjust the correlated optics state and induce a parametric resonance to study ionization cooling under the resonant condition.

  10. Chemical Principles Revisited. Proton Magnetic Resonance Spectroscopy.

    ERIC Educational Resources Information Center

    McQuarrie, Donald A.

    1988-01-01

    Discusses how to interpret nuclear magnetic resonance (NMR) spectra and how to use them to determine molecular structures. This discussion is limited to spectra that are a result of observation of only the protons in a molecule. This type is called proton magnetic resonance (PMR) spectra. (CW)

  11. High efficiency cw laser-pumped tunable alexandrite laser

    SciTech Connect

    Lai, S.T.; Shand, M.L.

    1983-10-01

    High efficiency cw alexandrite laser operation has been achieved. With longitudinal pumping by a krypton laser in a nearly concentric cavity, a 51% output power slope efficiency has been measured. Including the transmission at the input coupler mirror, a quantum yield of 85% has been attained above threshold. Tunability from 726 to 802 nm has also been demonstrated. The low loss and good thermal properties make alexandrite ideal for cw laser operation.

  12. High power CW iodine laser pumped by solar simulator

    NASA Technical Reports Server (NTRS)

    Lee, Ja H.; Lee, Min H.; Weaver, Willard R.

    1987-01-01

    An iodine photodissociation laser was pumped by a long Ar arc as the solar simulator to produce a 10-W CW output. Continuous lasing for 1 h was achieved with a flow of the laser material n-C3F7I. The 10-W CW output is the highest produced to date and establishes the feasibility of developing a solar-pumped laser for space power transmission.

  13. 3 μm CW lasers for myringotomy and microsurgery.

    PubMed

    Linden, Kurt J; Pfeffer, Christian P; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S

    2013-03-01

    This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899. PMID:24382990

  14. Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations.

    PubMed

    Crăciun, Cora

    2014-08-01

    CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids' EPR behaviour, for different spin system symmetries. The metrics' efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method. PMID:24968092

  15. Non-volatile analysis in fruits by laser resonant ionization spectrometry: application to resveratrol (3,5,4'-trihydroxystilbene) in grapes

    NASA Astrophysics Data System (ADS)

    Montero, C.; Orea, J. M.; Soledad Muñoz, M.; Lobo, R. F. M.; González Ureña, A.

    A laser desorption (LD) coupled with resonance-enhanced multiphoton ionisation (REMPI) and time-of-flight mass spectrometry (TOFMS) technique for non-volatile trace analysis compounds is presented. Essential features are: (a) an enhanced desorption yield due to the mixing of metal powder with the analyte in the sample preparation, (b) a high resolution, great sensitivity and low detection limit due to laser resonant ionisation and mass spectrometry detection. Application to resveratrol content in grapes demonstrated the capability of the analytical method with a sensitivity of 0.2 pg per single laser shot and a detection limit of 5 ppb.

  16. Characterization by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of the major photoproducts of temoporfin (m-THPC) and bacteriochlorin (m-THPBC).

    PubMed

    Angotti, M; Maunit, B; Muller, J F; Bezdetnaya, L; Guillemin, F

    2001-07-01

    The photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (temoporfin, m-THPC) and 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (bacteriochlorin, m-THPBC) was studied in ethanol-water (1 : 99, v/v) and in physiological medium (phosphate-buffered saline, PBS) with or without fetal calf serum (FCS). m-THPC solution was irradiated with the laser radiation of 650 nm, whereas m-THPBC solution underwent two consecutive irradiations at 532 and 650 nm. The photoproducts were characterized by UV-visible absorption spectrophotometry and by matrix-assisted laser desorption/ionization (MALDI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Independent of the solvent used, the phototransformation of either photosensitizer yielded the formation of 5,10,15,20-tetrakis (m-hydroxyphenyl)porphyrin (m-THPP) through a major dehydrogenation process. PMID:11473406

  17. A near-surface plasma in the beam of a CW CO2 laser

    NASA Astrophysics Data System (ADS)

    Vasiltsov, V. V.; Zabelin, A. M.; Zakharkina, O. L.; Lebedev, F. V.; Minnebaev, K. F.

    1985-07-01

    The effect of CW radiation from a CO2 laser on the plasma forming near the surface of a heated metal has been investigated experimentally. The power density of the CO2 laser was 1 million W/sq cm and the metal samples included alloys of zinc, copper and aluminum. A stationary erosion flame was found forming on the surface of the metals in the absence of an optical test vapor. No ionization of the surrounding target air was observed when the power density of the laser was increased to 2 million W/sq cm, and the optical discharge did not move from the target along the path of the laser beam. The results are used to develop criteria for selecting the operating parameters of a laser-based metals processing system.

  18. Comparative Pharmacodynamics of Pancuronium, Cisatracurium, and CW002 in Rabbits

    PubMed Central

    Diaz, Leslie L; Zhang, Jingwei; Heerdt, Paul M

    2014-01-01

    Pancuronium is a long-duration neuromuscular blocking drug (NMBD) that has been used in anesthetized rabbits at 0.1 mg/kg. However, there are limited data regarding the time course for recovery from this dose either spontaneously or with pharmacologic reversal. Here we defined the potency, onset, and recovery characteristics for the intermediate-duration NMBD cisatracurium and CW002 (a novel cysteine-inactivated molecule) in the rabbit, and test the hypothesis that these drugs may be alternatives to 0.1 mg/kg pancuronium for survival procedures. New Zealand white rabbits anesthetized with isoflurane were studied in a cross-over design. Potencies of cisatracurium and CW002 were defined as the effective dose for 95% depression of evoked muscle twitch (ED95). Responses to 3×ED95 were used to define onset (time to maximal effect), recovery index (RI; time from 25% to 75% recovery of twitch), and duration (time to complete recovery). Responses to all drugs were determined with and without reversal by neostigmine–glycopyrrolate or l-cysteine. CW002 was 4-fold more potent than was cisatracurium, but their onset, RI, and duration were similar. Pancuronium had similar onset and RI but longer duration, compared with cisatracurium and CW002. Reversal shortened the recovery index and duration for all 3 drugs. At 3×ED95, cisatracurium and CW002 had the same onset as did standard-dose pancuronium, but durations were shorter and more predictable. In addition, CW002 can be reversed without the potential side effects of cholinergic manipulation. We conclude that cisatracurium and CW002 are viable alternatives to pancuronium for survival studies in rabbits. PMID:24827571

  19. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    SciTech Connect

    Unruh, W.P.; Wolf, M.A.; Bluestein, H.B.

    1988-01-01

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm. 2 refs., 2 figs.

  20. Ionization chamber

    DOEpatents

    Walenta, Albert H.

    1981-01-01

    An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.

  1. Ionization chamber

    DOEpatents

    Walenta, A.H.

    An ionization chamber is described which has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionizes the gas.

  2. IONIZATION CHAMBER

    DOEpatents

    Redman, W.C.; Shonka, F.R.

    1958-02-18

    This patent describes a novel ionization chamber which is well suited to measuring the radioactivity of the various portions of a wire as the wire is moved at a uniform speed, in order to produce the neutron flux traverse pattern of a reactor in which the wire was previously exposed to neutron radiation. The ionization chamber of the present invention is characterized by the construction wherein the wire is passed through a tubular, straight electrode and radiation shielding material is disposed along the wire except at an intermediate, narrow area where the second electrode of the chamber is located.

  3. On the measurement of wind speeds in tornadoes with a portable CW/FM-CW Doppler radar

    SciTech Connect

    Bluestein, H.B. . School of Meteorology); Unruh, W.P. )

    1991-01-01

    Both the formation mechanism and structure of tornadoes are not yet well understood. The Doppler radar is probably the best remote-sensing instrument at present for determining the wind field in tornadoes. Although much has been learned about the non-supercell tornado from relatively close range using Doppler radars at fixed sites, close-range measurements in supercell tornadoes are relatively few. Doppler radar can increase significantly the number of high-resolution, sub-cloud base measurements of both the tornado vortex and its parent vortex in supercells, with simultaneous visual documentation. The design details and operation of the CW/FM-CW Doppler radar developed at the Los Alamos National Laboratory and used by storm-intercept teams at the Univ. of Oklahoma are described elsewhere. The radar transmits 1 W at 3 cm, and can be switched back and forth between CW and FM-CW modes. In the FM-CW mode the sweep repetition frequency is 15.575 kHz and the sweep width 1.9 MHz; the corresponding maximum unambiguous range and velocity, and range resolution are 5 km, {plus minus} 115 m s{sup {minus}1}, and 78 m respectively. The bistatic antennas, which have half-power beamwidths of 5{degree}, are easily pointed wit the aid of a boresighted VCR. FM-CW Data are recorded on the VCR, while voice documentation is recorded on the audio tape; video is recorded on another VCR. The radar and antennas are easily mounted on a tripod, and can be set up by three people in a minute or two. The purpose of this paper is to describe the signal processing techniques used to determine the Doppler spectrum in the FM-CW mode and a method of its interpretation in real time, and to present data gathered in a tornadic storm in 1990. 15 refs., 7 figs.

  4. First experiments with gasdynamic ion source in CW mode.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Vodopyanov, A; Tarvainen, O

    2016-02-01

    A new type of ECR ion source-a gasdynamic ECR ion source-has been recently developed at the Institute of Applied Physics. The main advantages of such device are extremely high ion beam current with a current density up to 600-700 emA/cm(2) in combination with low emittance, i.e., normalized RMS emittance below 0.1 π mm mrad. Previous investigations were carried out in pulsed operation with 37.5 or 75 GHz gyrotron radiation with power up to 100 kW at SMIS 37 experimental facility. The present work demonstrates the first experience of operating the gasdynamic ECR ion source in CW mode. A test bench of SMIS 24 facility has been developed at IAP RAS. 24 GHz radiation of CW gyrotron was used for plasma heating in a magnetic trap with simple mirror configuration. Initial studies of plasma parameters were performed. Ion beams with pulsed and CW high voltage were successfully extracted from the CW discharge. Obtained experimental results demonstrate that all advantages of the gasdynamic source can be realized also in CW operation. PMID:26931933

  5. Relative merits of rCW(A) and XiX heteronuclear spin decoupling in solid-state magic-angle-spinning NMR spectroscopy: A bimodal Floquet analysis.

    PubMed

    Equbal, Asif; Leskes, Michal; Nielsen, Niels Chr; Madhu, P K; Vega, Shimon

    2016-02-01

    We present a bimodal Floquet analysis of the recently introduced refocused continuous wave (rCW) solid-state NMR heteronuclear dipolar decoupling method and compare it with the similar looking X-inverse X (XiX) scheme. The description is formulated in the rf interaction frame and is valid for both finite and ideal π pulse rCW irradiation that forms the refocusing element in the rCW scheme. The effective heteronuclear dipolar coupling Hamiltonian up to first order is described. The analysis delineates the difference between the two sequences to different orders of their Hamiltonians for both diagonal and off-diagonal parts. All the resonance conditions observed in experiments and simulations have been characterised and their influence on residual line broadening is highlighted. The theoretical comparison substantiates the numerical simulations and experimental results to a large extent.

  6. Studies of structural isomers o-, m-, and p-fluorophenylacetylene by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy.

    PubMed

    Shivatare, Vidya S; Kundu, Aniket; Patwari, G Naresh; Tzeng, Wen Bih

    2014-09-18

    We report the vibrational spectra of o-fluorophenylacetylene (OFPA), m-fluorophenylacetylene (MFPA), and p-fluorophenylacetylene (PFPA) in the electronically excited S1 and cationic ground D0 states. These new data show that the relative location of the fluorine atom with respect to the acetylenic group can influence the transition energy and molecular vibration. The adiabatic ionization energies of these structural isomers follow the order: PFPA < OFPA < MFPA. It is found that the molecular geometries of these molecules in the D0 state resemble those in the S1 state. Detailed spectral analysis suggests that the in-plane ring deformation vibrations are slightly "harder" in the D0 state than the corresponding ones in the S1 state.

  7. CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: solving a lineshape paradox.

    PubMed

    Delpoux, Olivier; Gourier, Didier; Binet, Laurent; Vezin, Hervé; Derenne, Sylvie; Robert, François

    2008-05-01

    Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4x10(19) spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S=1/2, and centres with S=0 ground state and thermally accessible triple state S=1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and (13)C nuclei indicates that IOM* centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H approximately 1.5+/-0.5x10(-2) of the order of values existing in interstellar medium.

  8. CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox

    NASA Astrophysics Data System (ADS)

    Delpoux, Olivier; Gourier, Didier; Binet, Laurent; Vezin, Hervé; Derenne, Sylvie; Robert, François

    2008-05-01

    Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4 × 10 19 spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S = 1/2, and centres with S = 0 ground state and thermally accessible triple state S = 1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and 13C nuclei indicates that IOM rad centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H ≈ 1.5 ± 0.5 × 10 -2 of the order of values existing in interstellar medium.

  9. SRF cavities for CW option of Project X Linac

    SciTech Connect

    Solyak, N.; Gonin, I.; Khabiboulline, T.; Lunin, A.; Perunov, N.; Yakovlev, V.; /Fermilab

    2009-09-01

    Alternative option of Project X is based on the CW SC 2GeV Linac with the average current 1mA. Possible option of the CW Linac considered in the paper includes low energy part consisted of a few families SC Spoke cavities (from 2.5 MeV to 466 MeV) and high energy part consisted of 2 types of elliptical cavities (v/c=0.81 and v/c=1). Requirements and designed parameters of cavities are considered.

  10. A sensitive and high dynamic range cw laser power meter

    NASA Astrophysics Data System (ADS)

    Krishnan, S.; Bindra, K. S.; Oak, S. M.

    2008-12-01

    We report the design of a cost effective, highly sensitive cw laser power meter with a large dynamic range based on a photodiode. The power meter consists of a photodiode, a current to voltage converter circuit, an offset balancing circuit, a microcontroller, an analog to digital converter, reed relays, and an alphanumeric liquid crystal display. The power meter can record absolute laser power levels as low as 1 pW. The dynamic range measured with a cw laser at a wavelength of 532 nm is 8×1010. The high sensitivity and large dynamic range are achieved by the implementation of an analog background balancing circuit and autoranging.

  11. Time Shifted PN Codes for CW Lidar, Radar, and Sonar

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor); Prasad, Narasimha S. (Inventor); Harrison, Fenton W. (Inventor); Flood, Michael A. (Inventor)

    2013-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  12. cw passive mode locking of a Ti:sapphire laser

    SciTech Connect

    Sarukura, N.; Ishida, Y.; Nakano, H.; Yamamoto, Y. )

    1990-02-26

    cw passive mode locking of a Ti:sapphire laser is achieved with 1,1{prime}-dietyl-2,2{prime}-dicarbocyanine iodide as the saturable absorber dye, using a 5 {mu}m thin dye jet flow. The pulse width is 4.0 ps, which is almost the transform-limited pulse for the observed spectrum width. The output power is {similar to}50 mW, when it is pumped by a 5 W cw Ar laser, while the tuning range is 745--755 nm.

  13. Ionization probes of molecular structure and chemistry

    SciTech Connect

    Johnson, P.M.

    1993-12-01

    Various photoionization processes provide very sensitive probes for the detection and understanding of the spectra of molecules relevant to combustion processes. The detection of ionization can be selective by using resonant multiphoton ionization or by exploiting the fact that different molecules have different sets of ionization potentials. Therefore, the structure and dynamics of individual molecules can be studied even in a mixed sample. The authors are continuing to develop methods for the selective spectroscopic detection of molecules by ionization, and to use these methods for the study of some molecules of combustion interest.

  14. Toward an integrated computational approach to CW-ESR spectra of free radicals.

    PubMed

    Barone, Vincenzo; Polimeno, Antonino

    2006-10-28

    Interpretation of structural properties and dynamic behaviour of molecules in solution is of fundamental importance to understand their stability, chemical reactivity and catalytic action. Information can be gained, in principle, by a variety of spectroscopic techniques, magnetic as well as optical. In particular, continuous wave electron spin resonance (CW-ESR) measurements are highly informative. However, the wealth of structural and dynamic information which can be extracted from ESR spectroscopy is, at present, limited by the necessity of employing computationally efficient models, which are increasingly complex as they need to take into account diverse relaxation processes affecting the spectrum. In this paper, we address the basic theoretical tools needed to predict, essentially ab initio, CW-ESR spectra observables according to the stochastic Liouville equation (SLE) approach, combined with quantum mechanical and hybrid methods for the accurate and efficient computation of structural, spectroscopic and magnetic properties of molecular systems. We shall discuss, on one hand, the quantum mechanical calculation of magnetic observables, via density functional theory (DFT), time-dependent DFT (TD-DFT) and application of the polarizable continuum model (PCM) for the description of environmental effects, including anisotropic environments and systems where different regions are characterized by different dielectric constants. One the other hand, the explicit evaluation of dynamical effects will be discussed based on the numerically exact treatment of the SLE in the presence of several relaxation processes, which has been proven to be a challenging task.

  15. CW RF system of the Project-X accelerator front end

    SciTech Connect

    Khabiboulline, T.; Barbanotti, S.; Gonin, I.; Solyak, N.; Terechkine, I.; Yakovlev, V.; /Fermilab

    2010-09-01

    Front end of a CW linac of the Project X contains an H{sup -} source, an RFQ, a medium energy transport line with the beam chopper, and a SC low-beta linac that accelerates H{sup -} from 2.5 MeV to 160 MeV. SC Single Spoke Resonators (SSR) will be used in the linac, because Fermilab already successfully developed and tested a SSR for beta = 0.21. Two manufactured cavities achieve 2.5 times more than design accelerating gradients. One of these cavities completely dressed, e.g. welded to helium vessel with integrated slow and fast tuners, and tested in CW regime. Successful tests of beta = 0.21 SSR give us a confidence to use this type of cavity for low beta (0.117) and for high-beta (0.4) as well. Both types of these cavities are under development. In present report the basic constrains, parameters, electromagnetic and mechanical design for all the three SSR cavities, and first test results of beta = 0.21 SSR are presented.

  16. New aspects in fragmentation of peptide nucleic acids: comparison of positive and negative ions by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Ziehe, Matthias; Grossmann, Tom N; Seitz, Oliver; Linscheid, Michael W

    2009-04-01

    The use of peptide nucleic acids (PNAs) is steadily increasing in biochemistry and diagnostics. So far, PNAs have mostly been investigated using cationic conditions in mass spectrometry. Furthermore, the use of fragmentation techniques developed for peptides and proteins like infrared multiphoton dissociation (IRMPD) and electron capture dissociation (ECD) has barely been examined. However, especially the fragmentation behavior of PNA oligomers in negative ion mode is of high importance, due to the ability to interact with nucleic acids which are almost exclusively analyzed in the negatively charged state. In the current study PNA fragmentations under cationic and anionic conditions were investigated and different fragmentation techniques like collision-induced dissociation (CID), IRMPD and ECD were applied. Especially when using CID and IRMPD, amide bonds were broken, whereas ECD resulted in the elimination of nucleobases. Differences were also observed between positive and negative ionization, while the sequence coverage for the negative ions was superior to positive ions. The fragmentation behavior using IRMPD led to almost complete sequence coverage. Additionally, in anions the interesting effect of multiple eliminations of HNCO was found. PMID:19280610

  17. A new technique for unbiased external ion accumulation in a quadrupole two-dimensional ion trap for electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Belov, M E; Nikolaev, E N; Alving, K; Smith, R D

    2001-01-01

    External ion accumulation in a two-dimensional (2D) multipole trap has been shown to increase the sensitivity, dynamic range and duty cycle of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. However, it is important that trapped ions be detected without significant bias at longer accumulation times in the external 2D multipole trap. With increasing ion accumulation time pronounced m/z discrimination was observed when trapping ions in an accumulation quadrupole. In this work we show that superimposing lower rf-amplitude dipolar excitation over the main rf-field in the accumulation quadrupole results in disruption of the m/z discrimination and can potentially be used to achieve unbiased external ion accumulation with FTICR.

  18. Resonance-enhanced multiphoton ionization of van der Waals molecules: Studies of spectroscopic shifts of phenyl acetylene clustered with molecules and atoms

    NASA Astrophysics Data System (ADS)

    Dao, P. D.; Morgan, S.; Castleman, A. W., Jr.

    1984-10-01

    Van der Waals molecules comprised of phenyl acetylene (PA) clustered with rare-gas atoms, R (R = Ne, Ar, Kr, Xe) and other molecules, M (M = N 2, O 2, N 2O, CO 2), H 2O, CCl 4, and NH 3) were formed via adiabatic expansion from a pulsed nozzle, subjected to resonance-erhanced MPI, and analyzed in a time-of-flight mass spectrometer. Studies of the perturbed L b( 1B 2) states reveal spectral shifts with respect to the aromatic molecule monomer. In the case of the rare-gas atoms the shift in frequency, which is red, linearly increases with the polarizability of the atom. Red-shifts were also seen for all other molecules except CO 2 and H 2O, where an appreciable blue-shift was observed in the case of the latter.

  19. Applications of KHZ-CW Lidar in Ecological Entomology

    NASA Astrophysics Data System (ADS)

    Malmqvist, Elin; Brydegaard, Mikkel

    2016-06-01

    The benefits of kHz lidar in ecological entomology are explained. Results from kHz-measurements on insects, carried out with a CW-lidar system, employing the Scheimpflug principle to obtain range resolution, are presented. A method to extract insect events and analyze the large amount of lidar data is also described.

  20. Nonlinear optical properties of methyl red under CW irradiation

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Ye, Qing; Wang, Chen; Wang, Jin; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2015-12-01

    Organic materials have wide potential application in nonlinear optical devices. The nonlinear optical (NLO) properties of methyl red (MR) doped polymethyl methacrylate (MR-PMMA) are investigated under CW laser irradiation at 473 nm, 532 nm and 632.8 nm, respectively. By combining Kramers-Kronig (K-K) relation and CW Z-scan technique, the effective refractive index n2 and the change of refractive index Δn are obtained under different scanning speed at 473 nm and 532 nm. Δn is positive at 473 nm, while Δn is negative at 532 nm. The experimental result is consistent with that of K-K relation. With the scanning speed decreasing, the NLO properties of MR-PMMA are enhanced. With different laser powers at 632.8 nm, MR-PMMA has only nonlinear absorption rather than nonlinear refraction. Meanwhile, the sample is investigated under pulse laser irradiation at 532 nm. Through the comparison of results of CW Z-scan and pulse Z-scan, the influence of the cumulative thermal effect on NLO properties of material is investigated. The results indicate that, under CW irradiation near the absorption peak wavelength, the cumulative thermal effect has great influence to the NLO properties of MR-PMMA.

  1. CW-FIT: Group Contingency Effects across the Day

    ERIC Educational Resources Information Center

    Wills, Howard P.; Iwaszuk, Wendy M.; Kamps, Debra; Shumate, Emily

    2014-01-01

    This study explored the effects of a group-contingency intervention on student behavior across academic instructional periods. Research suggests group contingencies are evidence-based practices, yet calls for investigation to determine the best conditions and groups suited for this type of intervention. CW-FIT (Class-Wide Function-related…

  2. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  3. Quantum mechanical features of optically pumped CW FIR lasers

    NASA Technical Reports Server (NTRS)

    Seligson, D.; Leite, J. R. R.; Sanchez, A.; Feld, M. S.; Ducloy, M.

    1977-01-01

    Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.

  4. Biodegradation of pyrazosulfuron-ethyl by Acinetobacter sp. CW17.

    PubMed

    Wang, Yanhui; Du, Liangwei; Chen, Yingxi; Liu, Xiaoliang; Zhou, Xiaomao; Tan, Huihua; Bai, Lianyang; Zeng, Dongqiang

    2012-03-01

    The pyrazosulfuron-ethyl-degrading bacterium, designated as CW17, was isolated from contaminated soil near the warehouse of the factory producing pyrazosulfuron-ethyl in Changsha city, China. The strain CW17 was identified as Acinetobacter sp. based on analyses of 94 carbon source utilization or chemical sensitivity in Biolog microplates, conventional phenotypic characteristics, and 16S rRNA gene sequencing. When pyrazosulfuron-ethyl was provided as the sole carbon source, the effects of pyrazosulfuron-ethyl concentration, pH, and temperature on biodegradation were examined. The degradation rates of pyrazosulfuron-ethyl at initial concentrations of 5.0, 20.0, and 50.0 mg/L were 48.0%, 77.0%, and 32.6%, respectively, after inoculation for 7 days. The growth of the strain was inhibited at low pH buffers. The chemical degradation occurs much faster at low pH than at neutral and basic pH conditions. The degradation rate of pyrazosulfuron-ethyl at 30°C was faster than those at 20 and 37°C by CW17 strains. Two metabolites of degradation were analyzed by liquid chromatography-mass spectroscopy (LC/MS). Based on the identified products, strain CW17 seemed to be able to degrade pyrazosulfuron-ethyl by cleavage of the sulfonylurea bridge. PMID:22388979

  5. Cascaded combiners for a high power CW fiber laser

    NASA Astrophysics Data System (ADS)

    Tan, Qirui; Ge, Tingwu; Zhang, Xuexia; Wang, Zhiyong

    2016-02-01

    We report cascaded combiners for a high power continuous wave (CW) fiber laser in this paper. The cascaded combiners are fabricated with an improved lateral splicing process. During the fusing process, there is no stress or tension between the pump fiber and the double-cladding fiber. Thus, the parameters of the combiner are better than those that have been reported. The coupling efficiency is 98.5%, and the signal insertion loss is 1%. The coupling efficiency of the cascaded combiners is 97.5%. The pump lights are individually coupled into the double-cladding fiber via five combiners. The thermal effects cannot cause damage to the combiners and the cascaded combiners can operate stably in high power CW fiber lasers. We also develop a high power CW fiber laser that generates a maximum 780 W of CW signal power at 1080 nm with 71% optical-to-optical conversion efficiency. The fiber laser is pumped via five intra-cavity cascaded combiners and five extra-cavity cascaded combiners with a maximum pump power of 1096 W and a pump wavelength of 975 nm.

  6. Experimental Investigation of Continuous-Wave Laser Ionization of Krypton

    SciTech Connect

    Cannon, Bret D.; Shannon, Robert F.

    2001-10-30

    This report describes experimental investigations of a method that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The experiments show that the ionization rate is at least a factor of 100 lower than calculated with our model that has been described in a previous report. This discrepancy may be due to a much smaller excitation cross section that expected based on previous work and/or the aberrations in the ultraviolet beam used for the first step in the excitation. Additional problems with damage to mirrors, alignment instabilities, and manufacturers halting production of key products make this approach not worth further development at this time

  7. Stable 1.25 watts CW far infrared laser radiation at the 119 micron methanol line

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Pickett, Herbert M.

    1987-01-01

    Far-infrared CW radiation of 1.25 watts has been obtained at the 119 micron methanol line with a CO2 pump power of 125 watts, and the maximum frequency fluctuation of the free running laser is measured to be less than + or - 100 kHz per hour. Reflecting optics have been used, when possible, to minimize CO2 degradation, and the frequency stability is ensured by cooling the input and output couplers. The input and output assemblies within the lasing medium are enclosed to minimize the external effects on the cavity length and to eliminate the mechanical instabilities associated with the use of bellows. The vibrational bottle-neck is broken by cooling the resonator wall to 5 deg and adding He as the buffer gas.

  8. Development of a powerful continuously tunable mid-infrared cw PPLN OPO for trace gas detection

    NASA Astrophysics Data System (ADS)

    van Herpen, Maarten; te Lintel Hekkert, Sacco; Bisson, Scott E.; Harren, Frans J. M.

    2002-08-01

    A new Optical Parametric Oscillator for the mid infrared wavelength region of 3-3.8 micrometer is developed with an idler output power of more than 1 Watt. The OPO is pumped with a 10 Watt, cw, Nd:YAG Laser and consists of a bowtie ring cavity (FSR 320 MHz) resonating at the signal wavelength. The wavelength is controlled with a fan-out PPLN crystal and a low finesse intracavity Fabry-Perot. The idler output could be tuned over more than 24 Ghz modehop-free, by tuning the pump laser and keep the OPO cavity fixed. Mode hop tuning over 100 Ghz could be obtained changing the length of the intracavity Fabry-Perot. This high power OPO is combined with photoacoustic spectroscopy in order to develop a sensitive trace gas detector for LifeScience applications.

  9. Combining Two-Dimensional Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy, Imaging Desorption Electrospray Ionization Mass Spectrometry, and Direct Analysis in Real-Time Mass Spectrometry for the Integral Investigation of Counterfeit Pharmaceuticals

    PubMed Central

    Nyadong, Leonard; Harris, Glenn A.; Balayssac, Stéphane; Galhena, Asiri S.; Malet-Martino, Myriam; Martino, Robert; Parry, R. Mitchell; Wang, May Dongmei; Fernández, Facundo M.; Gilard, Véronique

    2016-01-01

    During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered 1H nuclear magnetic resonance spectroscopy (2D DOSY 1H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY 1H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug “chemotyping”. In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY 1H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials. PMID:19453162

  10. Nuclear magnetic resonance studies on the pKa values and interaction of ionizable groups in bromelain inhibitor VI from pineapple stem.

    PubMed

    Hatano, Ken-ichi; Kojima, Masaki; Tanokura, Masaru; Takahashi, Kenji

    2003-01-01

    Bromelain inhibitor VI (BI-VI), a cysteine proteinase inhibitor from pineapple stem, is a unique double-chain molecule composed of two distinct domains A and B. In order to clarify the molecular mechanism of the proteinase-inhibitor interaction, we investigated the electrostatic properties of this inhibitor. The inhibitory activity toward bromelain was revealed to be maximal at pH 3-4 and the gross conformation to be stable over a wide range of pH. Based on these results, pH titration experiments were performed on the proton resonances of BI-VI in the pH range of 1.5-9.9, and pKa values (pKexp) were determined for all carboxyl groups and alpha-amino groups. The pKexp were also compared with theoretical values calculated from the NMR-derived structures of BI-VI. The electrostatic surface potential map constructed using the pKexp values revealed that BI-VI possesses continuous negatively charged and scattered positively charged regions on the molecular surface and both regions appear to serve for docking properly with a basic target enzyme. Furthermore, it was suggested that the ionic interaction of the inhibitor with the target enzyme is primarily important for the inhibition, which seems to involve some carboxyl groups in the inhibitor and a thiol group in the proteinase.

  11. Experimental atomic scale investigation of irradiation effects in CW 316SS and UFG-CW 316SS

    NASA Astrophysics Data System (ADS)

    Pareige, P.; Etienne, A.; Radiguet, B.

    2009-06-01

    Materials of the core internals of pressurized water reactor (austenitic stainless steels) are subject to neutron irradiation. To understand the ageing mechanisms associated with irradiation and propose life predictions of components or develop new materials, irradiation damage needs to be experimentally investigated. Atomic scale investigation of a neutron-irradiated CW316 SS with the laser pulsed atom probe gives a detailed description of the solute segregation in the austenitic grains. In order to understand the mechanism of solute segregation detected in the neutron-irradiated materials, ion irradiations were performed. These latest irradiations were realized on a CW 316SS as well as on a nanostructured CW 316SS. The study of irradiation effects in a nanograin material allows first, to easily analyse grain boundary segregation and second, to test the behaviour under irradiation of a new nanostructured material. The three aspects of this atomic scale investigation (neutron irradiation effect, model ion irradiation, new nanostructured CW 316 SS) are tackled in this paper.

  12. The Fourier Transform in Chemistry. Part 1. Nuclear Magnetic Resonance: Introduction.

    ERIC Educational Resources Information Center

    King, Roy W.; Williams, Kathryn R.

    1989-01-01

    Using fourier transformation methods in nuclear magnetic resonance has made possible increased sensitivity in chemical analysis. This article describes these methods as they relate to magnetization, the RF magnetic field, nuclear relaxation, the RF pulse, and free induction decay. (CW)

  13. Screening of key antioxidant compounds of longan (Dimocarpus longan Lour.) seed extract by combining online fishing/knockout, activity evaluation, Fourier transform ion cyclotron resonance mass spectrometry, and high-performance liquid chromatography electrospray ionization mass spectrometry methods.

    PubMed

    Chen, Jinyu; Ge, Zhen-Zhen; Zhu, Wei; Xu, Ze; Li, Chun-Mei

    2014-10-01

    To figure out the key phenolic compounds accounting for the antioxidant effects of longan (Dimocarpus longan Lour.) seed extract, online fishing/knockout method, activity evaluation assays, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis were used jointly for the first time. p-Coumaric acid-glycoside, (S)-flavogallonic acid, ellagic acid derivative, and methyl-ellagic acid glucopyranoside were first identified in longan seeds. In addition, our study revealed that ellagic acid as well as its derivative and p-coumaric acid-glycoside had important contribution to the potent antioxidant activity of longan seed extract, while gallic acid, corilagin, (S)-flavogallonic acid, methyl-ellagic acid glucopyranoside, and ethyl gallate showed very little contribution to the total antioxidant activity of longan seed extract. The combining use of the online fishing/knockout method, activity evaluation assays, FT-ICR-MS, and HPLC-ESI-MS analysis is a useful and simple strategy for screening of key bioactive compounds from complex extracts.

  14. Temporal compression of cw diode-laser output into short pulses with cesium-vapor group-velocity dispersion.

    PubMed

    Choi, K; Menders, J; Ross, D; Korevaar, E

    1993-11-15

    Using a technique similar to chirped pulse compression, we have compressed the 50-mW cw output of a diode laser into pulses of greater than 500-mW peak power and less than 400-ps duration. By applying a small current modulation to the diode, we induced a small wavelength modulation in the vicinity of the 6s(1/2)-to-6p(3/2) cesium resonance transition at 852 nm. Group-velocity dispersion on propagation through a cesium vapor cell then led to pulse compression. We developed a simple model to make predictions of output pulse shapes by using different modulation waveforms. PMID:19829441

  15. Raman analysis of SF 6 molecular beams excited by a cw CO 2 laser

    NASA Astrophysics Data System (ADS)

    Luijks, G.; Timmerman, J.; Stolte, S.; Reuss, J.

    1983-06-01

    In a molecular beam the effects of vibrational pumping of SF 6 (ν 3 = 948 cm -1) are studied, using a line-tunable cw CO 2 laser. Intracavity spontaneous Raman scattering is used for analysis. For excitation in the collision regime ( xE/ D ≤ 1), a thermal redistribution of the ν 3 excitation over all vibrational modes is found, together with an average absorption up to six photons per molecule. The infrared absorption profile shows a red-shift of 6 cm -1. For excitation in the relatively rare collision regime ( xE/ D ⩾ 4), a structured non-thermal ν 1 Raman spectrum is observed, especially in the case of seeded molecular beams (10% in He). The observed hot-band peaks can be explained in terms of single-photon absorptions and collision-induced near-resonant V-V energy transfer, leading to single, double and triple excitations of the ν 3 mode. The value of Trot in the beam is found to influence sensitively the non-resonant energy-transfer rate [e.g. hν 3(948 cm -1)+Δ Erot → h(ν 4 + ν 6)(962 cm -1) relative to the near-resonant transfer rate ( hν 3 + hν 3 → 2 hν 3 + 3.5 cm -1)].

  16. New Vanadium Compounds in Venezuela Heavy Crude Oil Detected by Positive-ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhao, Xu; Shi, Quan; Gray, Murray R.; Xu, Chunming

    2014-06-01

    Metalloporphyrins are ubiquitous in nature, particularly iron porphyrins (hemes) and magnesium dihydroporphyrins or chlorophylls. Oxovanadium (IV) complexes of alkyl porphyrins are widely distributed in petroleum, oil shales and maturing sedimentary bitumen. Here we identify new vanadium compounds in Venezuela Orinoco heavy crude oil detected by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). These compounds likely have the main structure of porphyrin, with the addition of more aromatic rings, thiophene and amino functional groups, corresponding to molecular series of CnH2n-40N4V1O1 (36 <= n <= 58),CnH2n-42N4V1O1 (37 <= n <= 57),CnH2n-44N4V1O1 (38 <= n <= 59),CnH2n-46N4V1O1 (43 <= n <= 54),CnH2n-48N4V1O1 (45 <= n <= 55),CnH2n-38N4V1S1O1 (36 <= n <= 41),CnH2n-40N4V1S1O1 (35 <= n <= 51),CnH2n-42N4V1S1O1 (36 <= n <= 54),CnH2n-44N4V1S1O1 (41 <= n <= 55),CnH2n-46N4V1S1O1 (39 <= n <= 55),CnH2n-27N5V1O1 (29 <= n <= 40),CnH2n-29N5V1O1 (34 <= n <= 42),CnH2n-33N5V1O1 (31 <= n <= 38),CnH2n-35N5V1O1 (32 <= n <= 41),CnH2n-27N5V1O2 (32 <= n <= 41) and CnH2n-29N5V1O2 (33 <= n <= 42). These findings are significant for the understanding of the existing form of vanadium species in nature, and are helpful for enhancing the amount of information on palaeoenvironments and improving the level of applied basic theory for the processing technologies of heavy oils.

  17. New vanadium compounds in Venezuela heavy crude oil detected by positive-ion electrospray ionization fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Zhao, Xu; Shi, Quan; Gray, Murray R; Xu, Chunming

    2014-06-20

    Metalloporphyrins are ubiquitous in nature, particularly iron porphyrins (hemes) and magnesium dihydroporphyrins or chlorophylls. Oxovanadium (IV) complexes of alkyl porphyrins are widely distributed in petroleum, oil shales and maturing sedimentary bitumen. Here we identify new vanadium compounds in Venezuela Orinoco heavy crude oil detected by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). These compounds likely have the main structure of porphyrin, with the addition of more aromatic rings, thiophene and amino functional groups, corresponding to molecular series of C(n)H(2n-40)N(4)V(1)O(1) (36 ≤ n ≤ 58),C(n)H(2n-42)N(4)V(1)O(1) (37 ≤ n ≤ 57),C(n)H(2n-44)N(4)V(1)O(1) (38 ≤ n ≤ 59),C(n)H(2n-46)N(4)V(1)O(1) (43 ≤ n ≤ 54),C(n)H(2n-48)N(4)V(1)O(1) (45 ≤ n ≤ 55),C(n)H(2n-38)N(4)V(1)S(1)O(1) (36 ≤ n ≤ 41),C(n)H(2n-40)N(4)V(1)S(1)O(1) (35 ≤ n ≤ 51),C(n)H(2n-42)N(4)V(1)S(1)O(1) (36 ≤ n ≤ 54),C(n)H(2n-44)N(4)V(1)S(1)O(1) (41 ≤ n ≤ 55),C(n)H(2n-46)N(4)V(1)S(1)O(1) (39 ≤ n ≤ 55),C(n)H(2n-27)N(5)V(1)O(1) (29 ≤ n ≤ 40),C(n)H(2n-29)N(5)V(1)O(1) (34 ≤ n ≤ 42),C(n)H(2n-33)N(5)V(1)O(1) (31 ≤ n ≤ 38),C(n)H(2n-35)N(5)V(1)O(1) (32 ≤ n ≤ 41),C(n)H(2n-27)N(5)V(1)O(2) (32 ≤ n ≤ 41) and C(n)H(2n-29)N(5)V(1)O(2) (33 ≤ n ≤ 42). These findings are significant for the understanding of the existing form of vanadium species in nature, and are helpful for enhancing the amount of information on palaeoenvironments and improving the level of applied basic theory for the processing technologies of heavy oils.

  18. New Vanadium Compounds in Venezuela Heavy Crude Oil Detected by Positive-ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    PubMed Central

    Zhao, Xu; Shi, Quan; Gray, Murray R.; Xu, Chunming

    2014-01-01

    Metalloporphyrins are ubiquitous in nature, particularly iron porphyrins (hemes) and magnesium dihydroporphyrins or chlorophylls. Oxovanadium (IV) complexes of alkyl porphyrins are widely distributed in petroleum, oil shales and maturing sedimentary bitumen. Here we identify new vanadium compounds in Venezuela Orinoco heavy crude oil detected by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). These compounds likely have the main structure of porphyrin, with the addition of more aromatic rings, thiophene and amino functional groups, corresponding to molecular series of CnH2n-40N4V1O1 (36 ≤ n ≤ 58),CnH2n-42N4V1O1 (37 ≤ n ≤ 57),CnH2n-44N4V1O1 (38 ≤ n ≤ 59),CnH2n-46N4V1O1 (43 ≤ n ≤ 54),CnH2n-48N4V1O1 (45 ≤ n ≤ 55),CnH2n-38N4V1S1O1 (36 ≤ n ≤ 41),CnH2n-40N4V1S1O1 (35 ≤ n ≤ 51),CnH2n-42N4V1S1O1 (36 ≤ n ≤ 54),CnH2n-44N4V1S1O1 (41 ≤ n ≤ 55),CnH2n-46N4V1S1O1 (39 ≤ n ≤ 55),CnH2n-27N5V1O1 (29 ≤ n ≤ 40),CnH2n-29N5V1O1 (34 ≤ n ≤ 42),CnH2n-33N5V1O1 (31 ≤ n ≤ 38),CnH2n-35N5V1O1 (32 ≤ n ≤ 41),CnH2n-27N5V1O2 (32 ≤ n ≤ 41) and CnH2n-29N5V1O2 (33 ≤ n ≤ 42). These findings are significant for the understanding of the existing form of vanadium species in nature, and are helpful for enhancing the amount of information on palaeoenvironments and improving the level of applied basic theory for the processing technologies of heavy oils. PMID:24948028

  19. PROSPECTS FOR A VERY HIGH POWER CW SRF LINAC

    SciTech Connect

    Robert Rimmer

    2010-06-01

    Steady development in SRF accelerator technology combined with the success of large scale installations such as CEBAF at Jefferson Laboratory and the SNS Linac at ORNL gives credibility to the concept of very high average power CW machines for light sources or Proton drivers. Such machines would be powerful tools for discovery science in themselves but could also pave the way to reliable cost effective drivers for such applications as neutrino factories, an energy-frontier muon collider, nuclear waste transmutation or accelerator driven subcritical reactors for energy production. In contrast to machines such as ILC that need maximum accelerating gradient, the challenges in these machines are mainly in efficiency, reliability, beam stability, beam loss and of course cost. In this paper the present state of the art is briefly reviewed and options for a multi-GeV, multi-MW CW linac are discussed.

  20. 100 GHz, 1 MW, CW gyrotron study program. Final report

    SciTech Connect

    Felch, K.; Bier, R.; Caplan, M.; Jory, H.

    1983-09-01

    The results of a study program to investigate the feasibility of various approaches in designing a 100 GHz, 1 MW CW gyrotron are presented. A summary is given of the possible configurations for a high average power, high frequency gyrotron, including an historical survey of experimental results which are relevant to the various approaches. A set of basic scaling considerations which enable qualitative comparisons between particular gyrotron interaction circuits is presented. These calculations are important in understanding the role of various electron beam and circuit parameters in achieving a viable gyrotron design. Following these scaling exercises, a series of design calculations is presented for a possible approach in achieving 100 GHz, 1 MW CW. These calculations include analyses of the electron gun and interaction circuit parts of the gyrotron, and a general analysis of other aspects of a high average power, high frequency gyrotron. Scalability of important aspects of the design to other frequencies is also discussed, as well as key technology issues.

  1. Centered CW interference rejection using spread spectrum techniques

    NASA Technical Reports Server (NTRS)

    Scholtz, R. A.

    1980-01-01

    A mathematical model is developed for the rejection of CW interference by spread spectrum techniques. When this interference is known to be exactly at the carrier frequency of the spread spectrum signal, this information can be used to design optimal IF filtering prior to despreading. The application of this approach to the pilot beam receiver of the Solar Power Satellite is considered as an example.

  2. Laser Photon Force Measurements using a CW Laser

    NASA Technical Reports Server (NTRS)

    Gray, Perry; Edwards, David L.; Carruth, M. Ralph, Jr.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    The photon force resulting from the non-damaging impact of laser derived photons on a metallic target was measured using a vacuum compatible microbalance. This experiment quantitatively verified that the force resulting from laser photons impacting a reflective surface is measurable and predictable. The photon wavelength is 1064 mn and the laser is a multi-mode 30OW Nd YAG continuous wave (CW) laser.

  3. The eclipsing binary CW Eridani. [three-color photoelectric observation

    NASA Technical Reports Server (NTRS)

    Chen, K.-Y.

    1975-01-01

    Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.

  4. Low threshold CW Nc laser oscillator at 1060 nm study

    NASA Technical Reports Server (NTRS)

    Birnbaum, M.; Deshazer, L. G.

    1976-01-01

    A broad range of characteristics of neodymium/yag lasers were investigated. With Nd:YVO4 crystals, CW 1.06 mu lasers were operated with thresholds a factor of 2 lower than Nd:YAG and with greater slope efficiencies. Thus, the first step in the development of new oscillators suitable for application in high data rate laser communication systems which surpass the present performance of the Nd:YAG laser has been successfully demonstrated.

  5. Quantitative Analysis of Long Chain Fatty Acids Present in a Type I Kerogen Using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Compared with BF3/MeOH Methylation/GC-FID

    NASA Astrophysics Data System (ADS)

    Kamga, Albert W.; Behar, Fancoise; Hatcher, Patrick G.

    2014-05-01

    Long chain fatty acids (LCFAs) are present in various natural samples and are easily detectable using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) in negative ion mode. The capability of the ESI-FT-ICR-MS for quantifying LCFAs was evaluated by performing a standard addition followed by an internal standard methodology to several kerogen extracts using n-C20 fatty acid as standard. As the concentration of the standard increased, the magnitude of its peak ( m/z 311.29525) increased linearly but with two separate slopes, leaving the entire mass spectra relatively unchanged, which shows evidence of reproducibility. Response factors of other LCFAs are obtained using a standard addition approach. We employed five LCFA standards ( n-C15, n-C19, n-C24, n-C26, and n-C30) with different carbon numbers. This allowed us to determine the response factor of all fatty acids (with carbon number between 15 and 30) by plotting the slope of each standard versus its carbon number. With the observed response factors and use of the internal standard, the concentrations of LCFAs in four kerogen extracts were measured by ESI-FT-ICR-MS and compared with those from GC-FID. The carbon number distribution obtained by ESI-FT-ICR-MS matched well the GC-FID distribution (5%-50%) with the exception of C16 and C18, considering that ESI-FT-ICR-MS does not differentiate between normal and branched LCFAs, whereas GC-FID does. This allows one to quantitatively compare samples with a relatively similar matrix for specific compounds such as LCFAs with no need of time-consuming derivatization procedures. Moreover, the calibration can be extended to higher carbon numbers with ESI-FT-ICR-MS, beyond the capabilities of GC/MS.

  6. Identification and fragmentation pathways of caffeine metabolites in urine samples via liquid chromatography with positive electrospray ionization coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry.

    PubMed

    Bianco, Giuliana; Abate, Salvatore; Labella, Cristiana; Cataldi, Tommaso R I

    2009-04-01

    Liquid chromatography (LC) with positive ion electrospray ionization (ESI+) coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) was employed for the simultaneous determination of caffeine and its metabolites in human urine within a single chromatographic run. LC/ESI-FTICRMS led to the unambiguous determination of the molecular masses of the studied compounds without interference from other biomolecules. A systematic and comprehensive study of the mass spectral behaviour of caffeine and its fourteen metabolites by tandem mass spectrometry (MS/MS) was performed, through in-source ion trap collision-induced dissociation (CID) of the protonated molecules, [M+H](+). A retro-Diels-Alder (RDA) process along with ring-contraction reactions were the major fragmentation pathways observed during CID. The base peak of xanthine precursors originates from the loss of methyl isocyanate (CH(3)NCO, 57 Da) or isocyanic acid (HNCO, 43 Da), which in turn lose a CO unit. Also uric acid derivatives shared a RDA rearrangement as a common fragmentation process and a successive loss of CO(2) or CO. The uracil derivatives showed a loss of a ketene unit (CH(2)CO, 42 Da) from the protonated molecule along with the loss of H(2)O or CO. To assess the potential of the present method three established metabolite ratios to measure P450 CYP1A2, N-acetyltransferase and xanthine oxidase activities were evaluated by a number of identified metabolites from healthy human urine samples after caffeine intake. PMID:19260028

  7. A new pair of HLA-C alleles, Cw*12042 and Cw*1203, differing at the KIR-related dimorphism of codons 77-80.

    PubMed

    Vilches, C; Bunce, M; van Dam, M; de Pablo, R

    1998-01-01

    A previously unknown HLA-C variant of the Cw*12 group was identified by PCR-SSP from genomic DNA of cell NDS-JD. Molecular cloning and nucleotide sequence analysis permitted the characterization of the complete coding region of this new allele, Cw*12042. The new variant differs from the recently reported Cw*12041 by two silent changes at exons 2 and 3, and from Cw*1203 by coding changes at codons 77 and 80. Cw*1203 (Ser-Asn) and Cw*12042 (Asn-Lys) constitute the second known example of HLA-C alleles only differing at the KIR-related dimorphism of residues 77-80. The new allele is associated in cell NDS-JD with the haplotype HLA-A*2403, Cw*12042, B*51, DRB1*1502, DRB5*0102, DQB1*0601, possibly related from the evolutionary aspect to the ancestral haplotype A*2402, Cw*1202, B*5201, DRB1*1502, DRB5*0102, DQB1*0601.

  8. Diversity of HLA-B17 alleles and haplotypes in East Asians and a novel Cw6 allele (Cw*0604) associated with B*5701.

    PubMed

    Inoue, T; Ogawa, A; Tokunaga, K; Ishikawa, Y; Kashiwase, K; Tanaka, H; Park, M H; Jia, G J; Chimge, N O; Sideltseva, E W; Akaza, T; Tadokoro, K; Takahashi, T; Juji, T

    1999-06-01

    The distribution of HLA-B17 alleles and their association with HLA-A, -C and -DRB1 alleles were investigated in seven East Asian populations Japanese, South Korean, Chinese-Korean, Man, Northern Han, Mongolian and Buryat populations). The B17 alleles were identified from genomic DNA using group-specific polymerase chain reaction (PCR) followed by hybridization with sequence-specific oligonucleotide probes (SSOP). In all of these East Asian populations, except Japanese and Chinese-Koreans, B*5701 was detected and strongly associated with A*0101, Cw*0602 and DRB1*0701. In contrast, B*5801 was detected in all the seven populations and strongly associated with A*3303, Cw*0302, DRB1*0301 and DRB1*1302. The A*3303-Cw*0302-B*5801-DRB1*1302 haplotype was observed in South Korean, Chinese-Korean, Buryat and Japanese populations, while A*3303-Cw*0302-B*5801-DRB1*0301 was predominantly observed in the Mongolian population. A similar haplotype, A*0101-Cw*0302-B*5801-DRB1*1302, was observed in the Buryat population. A novel Cw6 allele, Cw*0604, was identified in the Man population. This Cw allele was observed on the haplotype A*0101-B*5701-DRB1*0701. Thus, we confirmed, at the sequence level, that the common haplotypes carrying B*5701 and B*5801 have been conserved and shared in East Asian populations.

  9. Self-consistent modeling for estimation of the reduced electric field in a DC excited diffusion controlled CW CO2 laser

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Bhagat, M. S.; Biswas, A. K.; Rana, L. B.; Pakhare, Jagdish; Rawat, B. S.; Kukreja, L. M.

    2016-07-01

    The results of a numerical simulation method that estimate various discharge parameters in the positive column of a DC glow discharge controlled by ambipolar diffusion are presented. The parameters like reduced electric field (E/N), electron temperature, ionization rates, ambipolar diffusion losses and the average gas temperature were numerically evaluated for several mixtures of CO2, N2 and He in low pressure regime. The estimated E/N value which is a primary governing parameter of positive column was verified experimentally using a double probe in diffusion controlled CW CO2 laser for a variety of CO2, N2 and He mixtures. The role of auxiliary ionization source like pulser used for pre-ionization and its effect on the steady state E/N value was also studied. A reasonably good agreement was found between the theoretical and the experimental results. Based on the results of this simulation a zigzag folded, diffusion-cooled, 500 W CW CO2 laser has been designed and developed for research in gas phase nanoparticle synthesis.

  10. Solvent effect on librational dynamics of spin-labelled haemoglobin by ED- and CW-EPR.

    PubMed

    Scarpelli, Francesco; Bartucci, Rosa; Sportelli, Luigi; Guzzi, Rita

    2011-03-01

    Two-pulse, echo-detected electron paramagnetic resonance (ED-EPR) spectra and continuous-wave EPR (CW-EPR) spectra were used to investigate the solvent effect on the librational motion of human haemoglobin spin-labelled on cysteine β93 with the nitroxide derivative of maleimide, 6-MSL. Protein samples fully hydrated in phosphate buffer solution (PBS), in a 60% v/v glycerol/water mixture and in the lyophilized form were measured at cryogenic temperature in the frozen state. The protein librational motion was characterized by the amplitude-correlation time product, <α²>τ(c), deduced from the ED-EPR spectra. The librational amplitude, <α²>τ(c), was determined independently, from the motionally averaged hyperfine splitting in the CW-EPR spectra, and the librational correlation time, τ(c), was derived from the combination of the pulsed and conventional EPR data. Rapid librational motion of small amplitude was detected in all samples. In each case, the librational dynamics was restricted up to 180 K, beyond which it increased steeply for the hydrated protein in PBS and in the presence of glycerol. In contrast, in the dehydrated protein, the librational dynamics was hindered and less dependent on temperature up to ~240 K. In all samples, <α²> deviated from small values only for T > 200 K, where a rapid increase of <α²> was evident for the hydrated samples, whereas limited temperature variation was shown in the lyophilized samples. The librational correlation time was in the sub-nanosecond regime and weakly dependent on temperature. The results evidence that solvent favours protein dynamics.

  11. Discharge-pumped cw gas lasers utilizing ``dressed-atom'' gain media

    NASA Astrophysics Data System (ADS)

    Sorokin, P. P.; Glownia, J. H.; Hodgson, R. T.

    2005-05-01

    The possibility of realizing an efficient gaseous laser-beam-generating medium that utilizes Λ -type coherently phased (i.e., “dressed”) atoms for the active laser species, but that does not inherently require the use of external laser beams for pumping, is explored. Specifically, it is investigated if multiphoton stimulated hyper-Raman scattering (SHRS) processes driven by fluorescence radiation generated in a continuous electrical discharge present within the vapor-containing cell could produce continuous-wave (cw) optical gain at the Λ -atom resonance frequencies ωo and ωo' . It is deduced that such gain could result from n -photon (n⩾4) SHRS processes only if absorption of fluorescence pump light occurs in the first three transitions of the n -photon sequence representing the process unit step. Estimates of the amount of optical gain that could be produced in such a system indicate that it should be sufficient to allow multiwatt cw laser operation to occur on one set of Λ transitions connecting levels in a “double- Λ ” structure, with the pump light being discharge-produced fluorescence centered about the transitions of the other Λ pair. However, to initiate operation of such a device would require injection into the laser optical cavity of intense “starter” laser pulses at both lasing frequencies. What should be an optimal experimental configuration for determining feasibility of the proposed laser device is described. In the suggested configuration, Cs-atom 6S1/2-6P1/2 transitions form the double- Λ structure.

  12. Production of High Intracavity UV Power From a CW Laser Source

    NASA Technical Reports Server (NTRS)

    David, R. T.; Chyba, T. H.; Keppel, C. E.; Gaskell, D.; Ent, R.

    1998-01-01

    The goal of this research project is to create a prototype high power CW source of ultraviolet (UV) photons for photon-electron scattering at the Thomas Jefferson National Accelerator Facility (TJNAF), Hall B. The facility will use optical resonant cavities to produce a high photon flux. The technical approach will be to frequency-double the 514.5 mn light from an Argon-Ion Laser to create 0.1 to 1.0 watt in the UV. The produced UV power will be stored in a resonant cavity to generate an high intracavity UV power of 102 to 103 watts. The specific aim of this project is to first design and construct the low-Q doubling cavity and lock it to the Argon-Ion wavelength. Secondly, the existing 514.5 nm high-Q build-up cavity and its locking electronics will be modified to create high intracavity UV power. The entire system will then be characterized and evaluated for possible beam line use.

  13. Stepped-frequency CW radar for concealed weapon detection and through-the-wall surveillance

    NASA Astrophysics Data System (ADS)

    Hunt, Allen R.; Hogg, R. Douglas

    2002-08-01

    Both concealed weapons detection and through the wall surveillance are significant problems for both law enforcement and military personnel. While on the surface it would appear that these two problems are unrelated technologically, they do, in fact, share some common ground. A concealed weapon acts as resonant object, exhibiting electromagnetic resonance peaks at frequencies characteristic of the weapon's major dimensions. For handguns the frequency range of interest lies approximately between 450 MHz and 2 GHz. As it turns out, this is also a region over which many common building materials are largely transparent. As part of grant 97-IJ-CX-K013 from the National Institute of Justice, AKELA, Inc. has developed a stepped-frequency, CW radar that covers this frequency range. The radar is digitally synthesized and controlled and has a range resolution of approximately 4'. Digital waveform control gives the radar the ability to avoid interference with other electronic devices, to tailor data collection for signal processing requirements, and to change its sweep time in response to operational requirements. AKELA has developed a brassboard concealed weapons detector that uses this radar. A through the wall imaging system that uses the radar is currently in development under AFRL Contract F30602-00-C-0205.

  14. Multiphoton ionization of ions, neutrals, and clusters. Progress report

    SciTech Connect

    Wessel, J.

    1991-06-28

    Scientific results are summarized from a three year research program on multiphoton ionization in aromatic molecules, clusters, and their ions. As originally proposed, the studies elucidated a new cluster ionization mechanism, characterized properties of long range intermolecular interactions, and investigated electronic transitions of aromatic cations cooled in a supersonic beam. The studies indicate that the new cluster ionization mechanism is highly efficient and dominates conventional 1 + 1 resonant ionization. In the case of the dimer of the large aromatic molecule fluorene, the results suggest that excimer formation competes with a direct ionization process. Highly selective excitonic spectra have been identified for several cluster species.

  15. How Suitable is Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight for Metabolite Imaging from Clinical Formalin-Fixed and Paraffin-Embedded Tissue Samples in Comparison to Matrix-Assisted Laser Desorption/Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry?

    PubMed

    Buck, Achim; Balluff, Benjamin; Voss, Andreas; Langer, Rupert; Zitzelsberger, Horst; Aichler, Michaela; Walch, Axel

    2016-05-17

    In research and clinical settings, formalin-fixed and paraffin-embedded (FFPE) tissue specimens are collected routinely and therefore this material constitutes a highly valuable source to gather insight in metabolic changes of diseases. Among mass spectrometry techniques to examine the molecular content of FFPE tissue, mass spectrometry imaging (MSI) is the most appropriate when morphological and histological features are to be related to metabolic information. Currently, high-resolution mass spectrometers are widely used for metabolomics studies. However, with regards to matrix-assisted laser desorption/ionization (MALDI) MSI, no study has so far addressed the necessity of instrumental mass resolving power in terms of clinical diagnosis and prognosis using archived FFPE tissue. For this matter we performed for the first time a comprehensive comparison between a high mass resolution Fourier-transform ion cyclotron resonance (FTICR) mass spectrometer and a time-of-flight (TOF) instrument with lower mass resolving power. Spectra analysis revealed that about one-third of the detected peaks remained unresolved by MALDI-TOF, which led to a 3-5 times lower number of m/z features compared to FTICR measurements. Overlaid peak information and background noise in TOF images made a precise assignment of molecular attributes to morphological features more difficult and limited classification approaches. This clearly demonstrates the need for high-mass resolution capabilities for metabolite imaging. Nevertheless, MALDI-TOF allowed reproducing and verifying individual markers identified previously by MALDI-FTICR MSI. The systematic comparison gives rise to a synergistic combination of the different MSI platforms for high-throughput discovery and validation of biomarkers.

  16. JLab CW Cryomodules for 4th Generation Light Sources

    SciTech Connect

    Rimmer, Robert; Bundy, Richard; Cheng, Guangfeng; Ciovati, Gianluigi; Clemens, William; Daly, Edward; Henry, James; Hicks, William; Kneisel, Peter; Manning, Stephen; Manus, Robert; Marhauser, Frank; Preble, Joseph; Reece, Charles; Smith, Karl; Stirbet, Mircea; Turlington, Larry; Wang, Haipeng; Wilson, Katherine

    2008-01-23

    Fourth generation light sources hold the prospect of unprecedented brightness and optical beam quality for a wide range of scientific applications. Many of the proposed new facilities will rely on large superconducting radio frequency (SRF) based linacs to provide high energy, low emittance CW electron beams. For high average power applications there is a growing acceptance of energy recovery linac (ERL) technology as the way to support large recirculating currents with modest RF power requirements. CW SRF and high current ERLs are two core competencies at Jefferson Lab. JLab has designed and built a number of CW cryomodules of several different types starting with the original CEBAF design, with variations for higher current in the two generations of JLab’s free-electron laser (FEL), through two intermediate prototypes to the final high-performance module for the 12 GeV upgrade. Each of these represent fully engineered and tested configurations with a variety of specifications that could be considered for possible use in fourth generation light sources. Furthermore JLab has been actively pursuing advanced concepts for highcurrent high-efficiency cryomodules for next generation ERL based FEL’s. These existing and proposed designs span the range from about 1mA single-pass to over 100 mA energy recovered current capability. Specialized configurations also exist for high-current non-energy recovered sections such as the injector region where very high RF power is required. We discuss the performance parameters of these existing and proposed designs and their suitability to different classes of fourth generation light sources.

  17. New frequency translation technique for FM-CW reflectometry.

    PubMed

    Meneses, Luis; Cupido, Luis; Manso, M E

    2010-10-01

    In broadband microwave reflectometry, coherent detection is widely used to obtain the phase information and to improve the systems sensitivity, both in diagnostics measuring the electronic density profile and plasma fluctuations. Coherent detection uses a translated version of the probing signal to guarantee a stable intermediate frequency. Here, a novel technique to generate the frequency translation by double frequency conversion is presented and its advantages over the commonly used single frequency conversion techniques employing image rejection mixers are discussed. The results obtained with the new frequency translator modules developed for the three JET FM-CW reflectometers, operating successfully at JET since mid-2009, are presented. PMID:21061479

  18. Quasi-CW Laser Diode Bar Life Tests

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

    1997-01-01

    NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

  19. Magnetism in the AM Herculis variable CW 1103+254

    SciTech Connect

    Schmidt, G.D.; Stockman, H.W.; Grandi, S.A.

    1983-08-15

    Time-resolved spectropolarimetry and spectrophotometry of the recently discovered magnetic binary CW 1103+254 reveal Zeeman-split Balmer polarization and absorption features corresponding to a mean photospheric field on the white dwarf primary of strength B = (19 +- 2) x 10/sup 6/ gauss. The orbital inclination i = 69/sup 0/ and latitude of the accreting magnetic pole ..delta.. = -56/sup 0/. With this perspective, we estimate the polar field strength B/sub p/ = (30 +- 5) x 10/sup 6/ gauss.

  20. Design of 250-MW CW RF system for APT

    SciTech Connect

    Rees, D.

    1997-09-01

    The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning.

  1. DC information preservation for cardiopulmonary monitor utilizing CW Doppler radar.

    PubMed

    Vergara, Alexander M; Boric-Lubecke, Olga; Lubecke, Victor M

    2008-01-01

    Direct conversion RF receivers introduce large DC offsets, reducing the dynamic range of the baseband signal. Coupled with the relatively small time varying signals in human vital sign monitoring using CW Doppler radar, extraction of cardio-pulmonary information becomes difficult. Previous DC offset compensation techniques utilizing AC coupling have proven detrimental to the performance of the system and the integrity of the low-frequency cardiopulmonary signals. A proposed system utilizing digitally controlled voltage feedback and center finding preserves the important DC information for optimal extraction of phase information in the quadrature system.

  2. High efficiency CW green-pumped alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Kuper, J. W.; Brown, D. C.

    2006-02-01

    High power, CW and pulsed alexandrite lasers were produced by pumping the laser rod with a high quality diode pumped 532 nm laser sources. This pumping architecture provides stable performance with output power > 1.4 W at 767nm in the free running mode and 0.78W at 1000 Hz. An output of 80 mW at 375.5 nm was achieved at 500 Hz. This approach holds promise for the production of a scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

  3. Experimental demonstration of CW light injection effect in upstream traffic TDM-PON

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Chow, Chi-Wai; Wu, Yu-Fu; Shih, Fu-Yuan; Chi, Sien

    2010-06-01

    High capacity time-division-multiplexed passive optical network (TDM-PON) is an emerging fiber access network that deploys optical access lines between a carrier's central office (CO) and a customer sites. In this investigation, we demonstrate and analyze the continuous wave (CW) upstream effect in TDM-PONs. Besides, we also propose and design a protection apparatus in each optical network unit (ONU) to avoid a CW upstream traffic in TDM-PONs due to sudden external environment change or ONU failure. When an upstream CW injection occurs in TDM access network, the protection scheme can stop the CW effect within a few ms to maintain the entire data traffic.

  4. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

    Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

    1995-01-01

    An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-851O network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

  5. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

    Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

    1995-01-01

    An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the first two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-X510 network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

  6. RF coupler for high-power CW FEL photoinjector

    SciTech Connect

    Kurennoy, S.; Young, L. M.

    2003-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. The design presently under way is a 100-mA 2.5-cell {pi}-mode, 700-MHz, normal conducting demonstration CW RF photoinjector. This photoinjector will be capable of accelerating 3 nC per bunch with an emittance at the wiggler less than 10 mm-mrad. The paper presents results for the RF coupling from ridged wave guides to hte photoinjector RF cavity. The LEDA and SNS couplers inspired this 'dog-bone' design. Electromagnetic modeling of the coupler-cavity system has been performed using both 2-D and 3-D frequency-domain calculations, and a novel time-domain approach with MicroWave Studio. These simulations were used to adjust the coupling coefficient and calculate the power-loss distribution on the coupling slot. The cooling of this slot is a rather challenging thermal management project.

  7. Photometric Analysis of the Overcontact Binary CW Cas

    NASA Astrophysics Data System (ADS)

    Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.

    2014-11-01

    New CCD photometric observations of overcontact binary CW Cas were carried out in 2004 and 2011. In particular, the light curve obtained in 2004 shows a remarkable O'Connell effect. Compared with light curves in different observing seasons, variations were found. These variations can be explained by dark spot activities on the surface of at least one component. Using the Wilson-Devinney code with a spot model, we find that the photometric solutions confirm CW Cas is a shallow W-subtype overcontact binary with a spotted massive component. Our new determined times of minimum light together with the others published in the literature were analyzed to find a change of orbital period. From the O - C curves, the period of the system shows a cyclic period change (P 3 = 69.9 yr, A 3 = 0.03196 days) superposed on the linear increase. The cyclic variation, if explained as the light-travel time effect, reveals the presence of a tertiary companion.

  8. Photometric analysis of the overcontact binary CW Cas

    SciTech Connect

    Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.

    2014-11-01

    New CCD photometric observations of overcontact binary CW Cas were carried out in 2004 and 2011. In particular, the light curve obtained in 2004 shows a remarkable O'Connell effect. Compared with light curves in different observing seasons, variations were found. These variations can be explained by dark spot activities on the surface of at least one component. Using the Wilson-Devinney code with a spot model, we find that the photometric solutions confirm CW Cas is a shallow W-subtype overcontact binary with a spotted massive component. Our new determined times of minimum light together with the others published in the literature were analyzed to find a change of orbital period. From the O – C curves, the period of the system shows a cyclic period change (P {sub 3} = 69.9 yr, A {sub 3} = 0.03196 days) superposed on the linear increase. The cyclic variation, if explained as the light-travel time effect, reveals the presence of a tertiary companion.

  9. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopes

    SciTech Connect

    Kudryavtsev, Yu. Ferrer, R.; Huyse, M.; Van den Bergh, P.; Van Duppen, P.; Vermeeren, L.

    2014-02-15

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented.

  10. Analysis of High Order Modes in 1.3 GHZ CW SRF Electron Linac for a Light Source

    SciTech Connect

    Sukhanov, A.; Vostrikov, A.; Yakovlev, V.

    2013-01-01

    Design of a Light Source (LS) based on the continuous wave superconducting RF (CW SRF) electron linac is currently underway. This facility will provide soft coherent X-ray radiation for a braod spectrum of basic research applications. Quality of the X-ray laser radiation is affected by the electron beam parameters such as the stability of the transverse beam position and longitudinal and transverse beam emittances. High order modes (HOMs) excited in the SRF structures by a passing beam may deteriorate the beam quality and affect the beam stability. Deposition of HOM energy in the walls of SRF cavities adds to the heat load of he cryogenic system and leads to the increased cost of building and operation of the linac. In this paper we evaluate effects of HOMs in an LS CW SRF linac based on Tesla-type 9-cell 1.3 GHz cavities. We analyze non-coherent losses and resonance excitation of HOMs. We estimate heat load due to the very high frequency HOMs. We study influence of the HOMs on the transverse beam dynamics.

  11. Locations of radical species in black pepper seeds investigated by CW EPR and 9 GHz EPR imaging

    NASA Astrophysics Data System (ADS)

    Nakagawa, Kouichi; Epel, Boris

    2014-10-01

    In this study, noninvasive 9 GHz electron paramagnetic resonance (EPR)-imaging and continuous wave (CW) EPR were used to investigate the locations of paramagnetic species in black pepper seeds without further irradiation. First, lithium phthalocyanine (LiPC) phantom was used to examine 9 GHz EPR imaging capabilities. The 9 GHz EPR-imager easily resolved the LiPC samples at a distance of ∼2 mm. Then, commercially available black pepper seeds were measured. We observed signatures from three different radical species, which were assigned to stable organic radicals, Fe3+, and Mn2+ complexes. In addition, no EPR spectral change in the seed was observed after it was submerged in distilled H2O for 1 h. The EPR and spectral-spatial EPR imaging results suggested that the three paramagnetic species were mostly located at the seed surface. Fewer radicals were found inside the seed. We demonstrated that the CW EPR and 9 GHz EPR imaging were useful for the determination of the spatial distribution of paramagnetic species in various seeds.

  12. Locations of radical species in black pepper seeds investigated by CW EPR and 9GHz EPR imaging.

    PubMed

    Nakagawa, Kouichi; Epel, Boris

    2014-10-15

    In this study, noninvasive 9GHz electron paramagnetic resonance (EPR)-imaging and continuous wave (CW) EPR were used to investigate the locations of paramagnetic species in black pepper seeds without further irradiation. First, lithium phthalocyanine (LiPC) phantom was used to examine 9GHz EPR imaging capabilities. The 9GHz EPR-imager easily resolved the LiPC samples at a distance of ∼2mm. Then, commercially available black pepper seeds were measured. We observed signatures from three different radical species, which were assigned to stable organic radicals, Fe(3+), and Mn(2+) complexes. In addition, no EPR spectral change in the seed was observed after it was submerged in distilled H2O for 1h. The EPR and spectral-spatial EPR imaging results suggested that the three paramagnetic species were mostly located at the seed surface. Fewer radicals were found inside the seed. We demonstrated that the CW EPR and 9GHz EPR imaging were useful for the determination of the spatial distribution of paramagnetic species in various seeds.

  13. Determination of the first ionization potential of actinium

    NASA Astrophysics Data System (ADS)

    Roßnagel, J.; Raeder, S.; Hakimi, A.; Ferrer, R.; Trautmann, N.; Wendt, K.

    2012-01-01

    Using resonance ionization spectroscopy the first-ionization potential of actinium has been determined by analyzing different Rydberg series in two-color resonant laser excitation. Three individual Rydberg series were investigated, converging toward the ionic ground state and toward the first- and second-excited state of the actinium ion, respectively. A combined analysis of the convergence limits leads to a consistent value for the first-ionization potential of Ac of 43394.45(19)cm-1, equivalent to 5.380226(24) eV.

  14. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

    1991-01-01

    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  15. Study of pseudo noise CW diode laser for ranging applications

    NASA Technical Reports Server (NTRS)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-01-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  16. Autoconfocal microscopy with a cw laser and thermionic detection.

    PubMed

    Lim, Daryl; Chu, Kengyeh K; Mertz, Jerome

    2008-06-15

    We introduce an application of thermionic emission in a PMT photocathode. Because of the nonlinear dependence of thermionic emission on absorbed laser power, a conventional PMT is found to produce a virtual pinhole effect that rejects unfocused light at least as strongly as a physical pinhole. This virtual pinhole effect is exploited in a scanning transmission confocal microscope equipped with a cw laser source. Because the area of the PMT photocathode is large, signal descanning is not required and thermionic detection acts as a self-aligned pinhole. Our technique of thermionic-detection autoconfocal microscopy is further implemented with graded-field contrast to obtain enhanced phase-gradient sensitivity in unlabeled samples, such as rat hippocampal brain slices.

  17. Operational experience with CW high gradient and high QL cryomodules

    SciTech Connect

    Hovater, J. Curt; Allison, Trent L.; Bachimanchi, Ramakrishna; Daly, Edward F.; Drury, Michael A.; Lahti, George E.; Mounts, Clyde I.; Nelson, Richard M.; Plawski, Tomasz E.

    2014-12-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of ten new 100 MV cryomodules (80 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. The RF system employs single cavity control using new digital LLRF controls and 13 kW klystrons. Recently, all of the new cryomodules and associated RF hardware and software have been commissioned and operated in the CEBAF accelerator. Electrons at linac currents up to 10 ?A have been successfully accelerated and used for nuclear physics experiments. This paper reports on the commissioning and operation of the cryomodules and RF system.

  18. Quasi-cw tissue transillumination at 1064 nm

    NASA Astrophysics Data System (ADS)

    Bernini, Umberto; Ramaglia, Antonio; Russo, Paolo

    1997-08-01

    An extended series of transillumination experiments has been performed in vitro on animal samples (bovine muscle, up to 30- mm-thick; chicken wing and quail femur, 12-mm-thick) and in vivo on the human hand (thickness, about 20 mm), using a pulsed light source (7 ns, about 10-4 J/pulse, 10 Hz rep rate) from a collimated (1.2 m) Nd:YAG laser beam (1064 nm). A PIN photodiode connected to a digital oscilloscope was used to measure the maximum intensity of the beam pulse transmitted through the sample (i.e., no temporal discrimination of the output signal was attempted) while it was scanned across the source/detector assembly. One dimensional scans were performed on bovine muscle samples in which thin metallic test objects were embedded, in order to study the spatial resolution of the technique (for bovine muscle at 1064 nm, absorption and reduced scattering coefficients are reported to be about 1 cm-1 and 3 cm-1, respectively). The measured spatial resolution was as good as 3.6 mm in 30 mm of tissue thickness. In the two-dimensional scans of the chicken and quail sample, fat and bone tissues can be easily seen with good resolution, whereas imaging of the middle finger of a human hand shows cartilaginoid and bone tissue with 1 - 2 mm resolution. Hence, this simple collimated quasi-cw technique gives significantly better results for tissue imaging than pure cw transillumination. Use of (pulsed) light above 1000 nm and a high energy content per pulse are supposed to explain the positive experimental findings.

  19. Ionization potentials of seaborgium

    SciTech Connect

    Johnson, E.; Pershina, V.; Fricke, B.

    1999-10-21

    Multiconfiguration relativistic Dirac-Fock values were calculated for the first six ionization potentials of seaborgium and of the other group 6 elements. No experimental ionization potentials are available for seaborgium. Accurate experimental values are not available for all of the other ionization potentials. Ionic radii for the 4+ through 6+ ions of seaborgium are also presented. The ionization potentials and ionic radii obtained will be used to predict some physiochemical properties of seaborgium and its compounds.

  20. Efficient, resonantly pumped, room-temperature Er3+:GdVO4 laser.

    PubMed

    Ter-Gabrielyan, N; Fromzel, V; Ryba-Romanowski, W; Lukasiewicz, T; Dubinskii, M

    2012-04-01

    We report an efficient room-temperature operation of a resonantly pumped Er3+:GdVO4 laser at 1598.5 nm. The maximum continuous wave (CW) output power of 3.5 W with slope efficiency of 56% was achieved with resonant pumping by an Er-fiber laser at 1538.6 nm. With pumping by a commercial laser diode bar stack, a quasi-CW (QCW) output of 7.7 W and maximum slope efficiency of ~53% versus absorbed pump power were obtained. This is believed to be the first resonantly (in-band) pumped, room-temperature Er3+:GdVO4 laser.

  1. Martian Meteor Ionization Layers

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Pesnell, W. D.

    1999-01-01

    Small interplanetary grains bombard Mars, like all the solar system planets, and, like all the planets with atmospheres, meteoric ion and atom layers form in the upper atmosphere. We have developed a comprehensive one-dimensional model of the Martian meteoric ionization layer including a full chemical scheme. A persistent layer of magnesium ions should exist around an altitude of 70 km. Unlike the terrestrial case, where the metallic ions are formed via charge-exchange with the ambient ions, Mg(+) in the Martian atmosphere is produced by photoionization. Nevertheless, the predicted metal layer peak densities for Earth and Mars are similar. Diffusion solutions, such as those presented here, should be a good approximation of the metallic ions in regions where the magnetic field is negligible and may provide a significant contribution to the nightside ionosphere. The low ultraviolet absorption of the Martian atmosphere may make Mars an excellent laboratory in which to study meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands.

  2. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  3. Unstable-stable resonators with toroidal mirrors.

    PubMed

    Borghese, A; Canevari, R; Donati, V; Garifo, L

    1981-10-15

    A resonator with toroidal mirrors is described. This resonator behaves like an off-axis unstable confocal resonator in one transverse dimension and like an on-axis concave-convex stable resonator in the other orthogonal dimension. Some experimental results are reported for a fast flow high power cw-CO(2) laser whose transverse cross section is restricted in the stable-resonator direction. These cavities allow an output laser beam with a fully illuminated cross section which is well suited for focusing. Moreover, the fraction of the available laser power which may be concentrated in the central lobe of the focal plane intensity distribution is 2.5-4.5 times higher than other unstable resonators with similarly restricted modal volumes. Finally the alignment requirements are examined. PMID:20372215

  4. High-throughput and high-sensitivity quantitative analysis of serum unsaturated fatty acids by chip-based nanoelectrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry: early stage diagnostic biomarkers of pancreatic cancer.

    PubMed

    Zhang, Yaping; Qiu, Ling; Wang, Yanmin; Qin, Xuzhen; Li, Zhili

    2014-04-01

    In this study, Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) coupled with chip-based direct-infusion nanoelectrospray ionization source (CBDInanoESI) in a negative ion mode is first employed to evaluate the effect of serum and its corresponding supernatant matrixes on the recoveries of serum free fatty acids (FFAs) based on spike-and-recovery experimental strategy by adding analytes along with analog internal standard (IS). The recoveries between serum (69.8-115.6%) and the supernatant (73.6-99.0%) matrixes are almost identical. Multiple point internal standard calibration curves between the concentration ratios of individual fatty acids to ISs, (C(17:1) as IS of C(16:1), C(18:3), C(18:2), or C(18:1) or C(21:0) as IS of C(20:4) or C(22:6)) versus their corresponding intensity ratios were constructed for C(16:1), C(18:3), C(18:2), C(18:1), C(20:4) and C(22:6), respectively, with correlation coefficients of greater than 0.99, lower limits of detection between 0.3 and 1.8 nM, and intra- and inter-day precision (relative standard deviations <18%), along with the linear dynamic range of three orders of magnitude. Sequentially, this advanced analytical platform was applied to perform simultaneous quantitative and qualitative analysis of multiple targets, e.g., serum supernatant unsaturated FFAs from 361 participants including 95 patients with pancreatic cancer (PC), 61 patients with pancreatitis and 205 healthy controls. Experimental results indicate that the levels of C(18:1), C(18:2), C(18:3), C(20:4) and C(22:6), as well as the level ratios of C(18:2)/C(18:1) and C(18:3)/C(18:1) of the PC patients were significantly decreased compared with those of healthy controls and the patients with pancreatitis (p < 0.01). It is worth noting that the ratio of C(18:2)/C(18:1), polyunsaturated fatty acids (PUFAs) (C(18:2), C(18:3), C(20:4), and C(22:6)), panel a (C(16:1), C(18:3), C(18:2), C(20:4) and C(22:6)) and panel b (C(18:2)/C(18:1) and C(18:3)/C(18

  5. Atmospheric-pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry.

    PubMed

    Constapel, M; Schellenträger, M; Schmitz, O J; Gäb, S; Brockmann, K J; Giese, R; Benter, Th

    2005-01-01

    We report on the development of a new laser-ionization (LI) source operating at atmospheric pressure (AP) for liquid chromatography/mass spectrometry (LC/MS) applications. APLI is introduced as a powerful addition to existing AP ionization techniques, in particular atmospheric-pressure chemical ionization (APCI), electrospray ionization (ESI), and atmospheric pressure photoionization (APPI). Replacing the one-step VUV approach in APPI with step-wise two-photon ionization strongly enhances the selectivity of the ionization process. Furthermore, the photon flux during an ionization event is drastically increased over that of APPI, leading to very low detection limits. In addition, the APLI mechanism generally operates primarily directly on the analyte. This allows for very efficient ionization even of non-polar compounds such as polycyclic aromatic hydrocarbons (PAHs). The APLI source was characterized with a MicroMass Q-Tof Ultima II analyzer. Both the effluent of an HPLC column containing a number of PAHs (benzo[a]pyrene, fluoranthene, anthracene, fluorene) and samples from direct syringe injection were analyzed with respect to selectivity and sensitivity of the overall system. The liquid phase was vaporized by a conventional APCI inlet (AP probe) with the corona needle removed. Ionization was performed through selective resonance-enhanced multi-photon ionization schemes using a high-repetition-rate fixed-frequency excimer laser operating at 248 nm. Detection limits well within the low-fmol regime are readily obtained for various aromatic hydrocarbons that exhibit long-lived electronic states at the energy level of the first photon. Only molecular ions are generated at the low laser fluxes employed ( approximately 1 MW/cm(2)). The design and performance of the laser-ionization source are presented along with results of the analysis of aromatic hydrocarbons.

  6. Broadly tunable resonant Raman gain and cw lasing in an optically thick Doppler-broadened medium

    NASA Astrophysics Data System (ADS)

    Popov, Alexander K.; Myslivets, Sergei A.; Hinze, Ulf; Tiemann, E.; Wellegehausen, Bernd; Tartakovsky, Gennady

    1999-09-01

    Interactive numerical simulator, based on MATLAB/SIMULINK platform, for virtual experimentation and optimization of frequency tunable optically pumped dimer laser has been created. Nonperturbative theory considering features of quantum coherence and interference effects at Doppler broadened transitions under two strong driving fields accounting for collisions and other kinetic processes in vapor-gas mixture as well as for propagation effects in optically thick medium is developed. The results are in good agreement with real experiments.

  7. The ionization energy of C2.

    PubMed

    Krechkivska, O; Bacskay, G B; Welsh, B A; Nauta, K; Kable, S H; Stanton, J F; Schmidt, T W

    2016-04-14

    Resonant two-photon threshold ionization spectroscopy is employed to determine the ionization energy of C2 to 5 meV precision, about two orders of magnitude more precise than the previously accepted value. Through exploration of the ionization threshold after pumping the 0-3 band of the newly discovered 4(3)Πg ← a(3)Πu band system of C2, the ionization energy of the lowest rovibronic level of the a(3)Πu state was determined to be 11.791(5) eV. Accounting for spin-orbit and rotational effects, we calculate that the ionization energy of the forbidden origin of the a(3)Πu state is 11.790(5) eV, in excellent agreement with quantum thermochemical calculations which give 11.788(10) eV. The experimentally derived ionization energy of X(1)Σg(+) state C2 is 11.866(5) eV. PMID:27083719

  8. The ionization energy of C2

    NASA Astrophysics Data System (ADS)

    Krechkivska, O.; Bacskay, G. B.; Welsh, B. A.; Nauta, K.; Kable, S. H.; Stanton, J. F.; Schmidt, T. W.

    2016-04-01

    Resonant two-photon threshold ionization spectroscopy is employed to determine the ionization energy of C2 to 5 meV precision, about two orders of magnitude more precise than the previously accepted value. Through exploration of the ionization threshold after pumping the 0-3 band of the newly discovered 43Πg←a3Πu band system of C2, the ionization energy of the lowest rovibronic level of the a3Πu state was determined to be 11.791(5) eV. Accounting for spin-orbit and rotational effects, we calculate that the ionization energy of the forbidden origin of the a3Πu state is 11.790(5) eV, in excellent agreement with quantum thermochemical calculations which give 11.788(10) eV. The experimentally derived ionization energy of X1Σg+ state C2 is 11.866(5) eV.

  9. Multiphoton ionization spectroscopy of the sodium dimer

    NASA Astrophysics Data System (ADS)

    Keller, John; Weiner, John

    1984-07-01

    We report an investigation of the role of molecular multiphoton ionization in the production of Na+2 when sodium vapor is subjected to intense optical radiation. Previous authors attribute the source of much of the ion dimer signal to laser-induced associative ionization of atom sodium. In this experiment, we distinguish the molecular process from atomic collisional mechanisms by producing an intense molecular beam created through free-jet expansion of the metal vapor. The beam of nearly 50% dimers cooled to their low rotational and vibrational states allow us to obtain a simplified three-photon ionization spectrum. We find that the spectrum displays two-photon resonances corresponding to known Rydberg level transitions and that the A state, acting as virtual intermediate, plays a crucial role in the large peak-to-peak intensity variations. We employ a simple model of multiphoton ionization which uses a rate-equation approach to generate a calculated spectrum. Based on the experimental results and the success of the model in reflecting them, we conclude that much of the highly structured component of the dimer ion signal reported previously under different experimental conditions is probably due to molecular multiphoton ionization but that this structure rides on a slowly varying broad signal envelope due to laser-induced associative ionization.

  10. Studies of narrow autoionizing resonances in gadolinium

    SciTech Connect

    Bushaw, Bruce A.; Nortershauser, W.; Blaum, K.; Wendt, Klaus

    2003-06-30

    The autoionization (AI) spectrum of gadolinium between the first and second limits has been investigated by triple-resonance excitation with high-resolution cw lasers. A large number of narrow AI resonances have been observed and assigned total angular momentum J values. The resonances are further divided into members of AI Rydberg series converging to the second limit or other ''interloping'' levels. Fine structure in the Rydberg series has been identified and interpreted in terms of Jc j coupling. A number of detailed studies have been performed on the interloping resonances: These include lifetime determination by lineshape analysis, isotope shifts, hyperfine structure, and photoionization saturation parameters. The electronic structure of the interloping levels is discussed in terms of these studies. Linewidths generally decrease with increasing total angular momentum and the J = 7 resonances are extremely narrow with Lorentzian widths ranging from < 1 MHz up to 157 MHz. The strongest resonances are found to have cross-sections of {approx}10-12 cm{sup 2} and photoionization can be saturated with powers available from cw diode lasers.

  11. CW high intensity non-scaling FFAG proton drivers

    SciTech Connect

    Johnstone, C.; Berz, M.; Makino, K.; Snopok, P.; /IIT, Chicago

    2011-04-01

    Accelerators are playing increasingly important roles in basic science, technology, and medicine including nuclear power, industrial irradiation, material science, and neutrino production. Proton and light-ion accelerators in particular have many research, energy and medical applications, providing one of the most effective treatments for many types of cancer. Ultra high-intensity and high-energy (GeV) proton drivers are a critical technology for accelerator-driven sub-critical reactors (ADS) and many HEP programs (Muon Collider). These high-intensity GeV-range proton drivers are particularly challenging, encountering duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotrons; a 10-20 MW proton driver is not presently considered technically achievable with conventional re-circulating accelerators. One, as-yet, unexplored re-circulating accelerator, the Fixed-field Alternating Gradient, or FFAG, is an attractive alternative to the cyclotron. Its strong focusing optics are expected to mitigate space charge effects, and a recent innovation in design has coupled stable tunes with isochronous orbits, making the FFAG capable of fixed-frequency, CW acceleration, as in the classical cyclotron. This paper reports on these new advances in FFAG accelerator technology and references advanced modeling tools for fixed-field accelerators developed for and unique to the code COSY INFINITY.

  12. CW laser compaction of aqueous solution deposited metal oxide films

    SciTech Connect

    Exarhos, G.J.; Dennis, T.

    1997-12-01

    Zirconium dioxide films were spin cast onto silica or silicon substrates from an aqueous solution comprised of the precursor metal nitrate and an organic complexant such as glycine. The hydrated films so derived consist of an amorphous organic phase in which the metal cations and nitrate anions are homogeneously dispersed. Heating to temperatures above 200 {degrees}C leads to film dehydration followed by an auto-catalyzed oxidation reaction whereby the bound nitrate oxidizes the organic matrix leaving behind an intact stoichiometric and crystalline metal oxide film. Films are characterized using AFM, XRD, and optical methods. Transformation processes in these films have been studied in detail by means of spectroscopic ellipsometry and laser induced fluorescence from films doped with a suitable rare earth probe ion such as SM{sup +3}. In the latter case, the measured fluorescence emission spectra are used to identify the hydrated, dehydrated, amorphous and crystalline metal oxide phases which evolve during processing. These transformations also have been induced upon visible CW laser irradiation at fluences in excess of 1 MW/cm{sup 2}. Under these conditions, the film dehydrates and compacts within the footprint of the incident laser beam rendering this region of the film water insoluble. Post irradiation washing of the film with water removes all vestiges of the film outside of the beam footprint suggesting a possible use of this technique for lithography applications. Films subjected to laser irradiation and post irradiation heating have been characterized with respect to thickness, phase composition, crystallite size and optical constants.

  13. Resonances and resonance widths

    SciTech Connect

    Collins, T.

    1986-05-01

    Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances.

  14. Analytical instruments, ionization sources, and ionization methods

    DOEpatents

    Atkinson, David A.; Mottishaw, Paul

    2006-04-11

    Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.

  15. Draft Genome Sequences of Ralstonia pickettii Strains SSH4 and CW2, Isolated from Space Equipment

    PubMed Central

    Monsieurs, Pieter; Mijnendonckx, Kristel; Provoost, Ann; Venkateswaran, Kasthuri; Ott, C. Mark; Leys, Natalie

    2014-01-01

    Ralstonia pickettii SSH4 and CW2 were isolated from space equipment. Here, we report their draft genome sequences with the aim of gaining insight into their potential to adapt to these environments. PMID:25189592

  16. CW 20 kW SAGE CO[sub 2] laser for industrial use. [Silent-discharge Assisted Glow discharge Excitation

    SciTech Connect

    Nagai, Haruhiko ); Hishii, Masao ); Tanaka, Masaaki; Myoi, Yasuhito; Yagi, Toshinori . Manufacturing Development Lab.); Wakata, Hitoshi . Central Research Lab.); Tabata, Norikazu . Industrial Electronics and Systems Lab.)

    1993-12-01

    A new type of high-power CW CO[sub 2] laser with power output of more than 20 kW is described. The laser consists of a discharge excitation system named SAGE (Silent-discharge (SD) Assisted Glow discharge Excitation) and a ZnSe or a KCl transmissive window to extract high quality beams with axisymmetric intensity profile from a confocal positive-branch unstable resonator. The SAGE is effective to form a uniformly distributed and stable discharge in a large-volume and high-pressure gas excitation medium. Together with appropriate high-pressure gas conditions leading to low dissociation rate of CO[sub 2] and with using the properly selected zeolite to adsorb water vapor in the laser chamber, the transmissive windows have enabled gas-sealed operations. Prior to the design of the 20-kW SAGE laser, small-scaled experiments of the SAGE and stress analyses of the window were studied. The structure of the 20-kW SAGE laser and its performance characteristics such as SD power, magnification factor of the unstable resonator and gas pressure dependences of the power output, long-term gas-sealed operation, and beam quality are described in detail. The maximum CW power of 26.5 kW with an efficiency of 16.5 percent is attained through the ZnSe window, and a 20.3 kW power output is extracted through the KCl window. A long-term gas-sealed operation at a CW power level of 20 kW is demonstrated during a period of 65 hours.

  17. Electron ionization of acetylene

    NASA Astrophysics Data System (ADS)

    King, Simon J.; Price, Stephen D.

    2007-11-01

    Relative partial ionization cross sections and precursor specific relative partial ionization cross sections for fragment ions formed by electron ionization of C2H2 have been measured using time-of-flight mass spectrometry coupled with a 2D ion-ion coincidence technique. We report data for the formation of H+, H2+, C2+, C+/C22+, CH +/C2H22+, CH2+, C2+, and C2H + relative to the formation of C2H2+, as a function of ionizing electron energy from 30-200eV. While excellent agreement is found between our data and one set of previously published absolute partial ionization cross sections, some discrepancies exist between the results presented here and two other recent determinations of these absolute partial ionization cross sections. We attribute these differences to the loss of some translationally energetic fragment ions in these earlier studies. Our relative precursor-specific partial ionization cross sections enable us, for the first time, to quantify the contribution to the yield of each fragment ion from single, double, and triple ionization. Analysis shows that at 50eV double ionization contributes 2% to the total ion yield, increasing to over 10% at an ionizing energy of 100eV. From our ion-ion coincidence data, we have derived branching ratios for charge separating dissociations of the acetylene dication. Comparison of our data to recent ab initio/RRKM calculations suggest that close to the double ionization potential C2H22+ dissociates predominantly on the ground triplet potential energy surface (Σg-3) with a much smaller contribution from dissociation via the lowest singlet potential energy surface (Δg1). Measurements of the kinetic energy released in the fragmentation reactions of C2H22+ have been used to obtain precursor state energies for the formation of product ion pairs, and are shown to be in good agreement with available experimental data and with theory.

  18. Family-wide Characterization of Histone Binding Abilities of Human CW Domain-containing Proteins.

    PubMed

    Liu, Yanli; Tempel, Wolfram; Zhang, Qi; Liang, Xiao; Loppnau, Peter; Qin, Su; Min, Jinrong

    2016-04-22

    Covalent modifications of histone N-terminal tails play a critical role in regulating chromatin structure and controlling gene expression. These modifications are controlled by histone-modifying enzymes and read out by histone-binding proteins. Numerous proteins have been identified as histone modification readers. Here we report the family-wide characterization of histone binding abilities of human CW domain-containing proteins. We demonstrate that the CW domains in ZCWPW2 and MORC3/4 selectively recognize histone H3 trimethylated at Lys-4, similar to ZCWPW1 reported previously, while the MORC1/2 and LSD2 lack histone H3 Lys-4 binding ability. Our crystal structures of the CW domains of ZCWPW2 and MORC3 in complex with the histone H3 trimethylated at Lys-4 peptide reveal the molecular basis of this interaction. In each complex, two tryptophan residues in the CW domain form the "floor" and "right wall," respectively, of the methyllysine recognition cage. Our mutation results based on ZCWPW2 reveal that the right wall tryptophan residue is essential for binding, and the floor tryptophan residue enhances binding affinity. Our structural and mutational analysis highlights the conserved roles of the cage residues of CW domain across the histone methyllysine binders but also suggests why some CW domains lack histone binding ability. PMID:26933034

  19. Forensic Application of FM-CW and Pulse Radar

    SciTech Connect

    S. K. Koppenjan; R. S. Freeland; M. L. Miller; R. E. Yoder

    2003-01-01

    Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar (200-700 MHz) (GPR-X) developed by the U.S. Department of Energy's (DOE) Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and 900 MHz)(GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled ''hot spots.'' The 400-MHz pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at 60 cm depth. The 400-MHz antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the 900-MHz antenna was able to penetrate slightly beyond 30 cm beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.

  20. The molecular determination of HLA-Cw alleles in the Mandenka (West Africa) reveals a close genetic relationship between Africans and Europeans.

    PubMed

    Sanchez-Mazas, A; Steiner, Q G; Grundschober, C; Tiercy, J M

    2000-10-01

    HLA-Cw alleles were determined by high-resolution polymerase chain reaction-sequence-specific oligonucleotide probe (PCR-SSOP) oligotyping in a sample of 165 Mandenka, a population from Eastern Senegal previously analysed for A/B and DRB/DQB polymorphisms. A total of 18 Cw alleles were identified, with Cw*0401/5 and 1601 accounting for a combined frequency of 36%. A comparison of Cw allele frequencies among several populations of different origins, Mandenka, Swiss, English, Ashkenazi Jews from the UK and Japanese, reveals a high genetic heterogeneity among them, but also a much closer relationship between Mandenka, Europeans and Ashkenazi than between any of these populations and Japanese. Cw*0501, Cw*0701 and Cw*1601, among others, appear to be restricted to the European and African populations. Many B-Cw haplotypes exhibit a significant linkage disequilibrium in the Mandenka, among which B*3501-Cw*0401 and B*7801-Cw*1601, formed by the most frequent B and Cw alleles, and B*5201-Cw*1601, B*5702-Cw*18 and B*4410-Cw*0401, not yet observed in other populations. B*3501-Cw*0401 is found with similar frequencies in Europeans. The results possibly support a close historical relationship between Africans and Europeans as compared to East Asiatics. However, the HLA-Cw frequency distributions are characterised by an excess of heterozygotes, indicating that balancing selection may have played a role in the evolution of this polymorphism.

  1. Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ueda, Keisuke; Matsuki, Yoh; Fujiwara, Toshimichi; Tatematsu, Yoshinori; Ogawa, Isamu; Idehara, Toshitaka

    2016-09-01

    A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz 1H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.

  2. High-power CW and long-pulse lasers in the green wavelength regime for copper welding

    NASA Astrophysics Data System (ADS)

    Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

    2016-03-01

    We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

  3. Discrimination of radiation quality through second harmonic out-of-phase cw-ESR detection.

    PubMed

    Marrale, Maurizio; Longo, Anna; Brai, Maria; Barbon, Antonio; Brustolon, Marina

    2014-02-01

    The ability to discriminate the quality of ionizing radiation is important because the biological effects produced in tissue strongly depends on both absorbed dose and linear energy transfer (LET) of ionizing particles. Here we present an experimental electron spin resonance (ESR) analysis aimed at discriminating the effective LETs of various radiation beams (e.g., 19.3 MeV protons, (60)Co photons and thermal neutrons). The measurement of the intensities of the continuous wave spectrometer signal channel first harmonic in-phase and the second harmonic out-of-phase components are used to distinguish the radiation quality. A computational analysis, was carried out to evaluate the dependence of the first harmonic in-phase and second harmonic out-of-phase components on microwave power, modulation amplitude and relaxation times, and highlights that these components could be used to point out differences in the relaxation times. On the basis of this numerical analysis the experimental results are discussed. The methodology described in this study has the potential to provide information on radiation quality. PMID:24524346

  4. Discrimination of radiation quality through second harmonic out-of-phase cw-ESR detection.

    PubMed

    Marrale, Maurizio; Longo, Anna; Brai, Maria; Barbon, Antonio; Brustolon, Marina

    2014-02-01

    The ability to discriminate the quality of ionizing radiation is important because the biological effects produced in tissue strongly depends on both absorbed dose and linear energy transfer (LET) of ionizing particles. Here we present an experimental electron spin resonance (ESR) analysis aimed at discriminating the effective LETs of various radiation beams (e.g., 19.3 MeV protons, (60)Co photons and thermal neutrons). The measurement of the intensities of the continuous wave spectrometer signal channel first harmonic in-phase and the second harmonic out-of-phase components are used to distinguish the radiation quality. A computational analysis, was carried out to evaluate the dependence of the first harmonic in-phase and second harmonic out-of-phase components on microwave power, modulation amplitude and relaxation times, and highlights that these components could be used to point out differences in the relaxation times. On the basis of this numerical analysis the experimental results are discussed. The methodology described in this study has the potential to provide information on radiation quality.

  5. Evidence of non-local impact ionization in CNT and HgCdTe

    NASA Astrophysics Data System (ADS)

    Marsland, J. S.; Atanu, A. G.

    2009-11-01

    Two aspects of the non-local nature of impact ionization, dead space and resonance, are investigated. The very small excess noise factor measured for mercury cadmium telluride photodiodes can only be explained if the hole to electron ionization coefficient ratio, k, is very small and the impact ionization dead space is also considered. A maximum value of k for HgCdTe is estimated in this paper. In addition, recent measurements of the reverse photocurrent in single wall carbon nanotubes show a well defined flat region at a multiplication of 1.6. This is argued to be evidence for resonant behaviour in impact ionization for carbon nanotubes.

  6. Multiphoton ionization of large water clusters.

    PubMed

    Apicella, B; Li, X; Passaro, M; Spinelli, N; Wang, X

    2014-05-28

    Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.

  7. Multiphoton ionization of large water clusters

    SciTech Connect

    Apicella, B.; Li, X.; Passaro, M.; Spinelli, N.; Wang, X.

    2014-05-28

    Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.

  8. Multiparticle Exciton Ionization in Shallow Doped Carbon Nanotubes.

    PubMed

    Sau, Jay D; Crochet, Jared J; Doorn, Stephen K; Cohen, Marvin L

    2013-03-21

    Shallow hole doping in small-diameter semiconducting carbon nanotubes with a valley degeneracy is predicted to result in the resonant ionization of excitons into free electron-hole pairs. This mechanism, which relies on the chirality of the electronic states, causes excitons to decay with high efficiencies where the rate scales as the square of the dopant density. Moreover, multiparticle exciton ionization can account for delocalized fluorescence quenching when a few holes per micrometer of tube length are present.

  9. The Rhodotron, a new 10 MeV, 100 kW, cw metric wave electron accelerator

    NASA Astrophysics Data System (ADS)

    Jongen, Y.; Abs, M.; Genin, F.; Nguyen, A.; Capdevila, J. M.; Defrise, D.

    1993-06-01

    New applications for high energy, high current electron beam processing are continually expanding. Today, however, 10 MeV rf electron linacs are frequently limited to an average beam power of only 20 or 30 kW. To achieve higher beam power, CW operation and the use of lower frequencies are necessary. In the last years, the principle for a new kind of electron accelerator was developed by the Atomic Energy Agency (CEA) in France. This accelerator is based on the principle of recirculating a beam throughout a single coaxial cavity resonating in metric waves. A 3.3 MeV, 4 mA prototype has been built and successfully tested. The industrial accelerator developed by IBA in collaboration with the CEA is a 10 MeV, 100 kW beam power unit with an additional beam exit at 5 MeV. The cavity, made of copper-plated steel, will resonate at 107.5 MHz. A rf power of 100 kW is needed to produce an electric field allowing an energy gain of 1 MeV per crossing. In addition, 100 kW of power is needed for acceleration. The 200 kW output amplifier uses a 100 kW plate dissipation tetrode (TH 681 from Thomson-CSF) in a grounded grid configuration. In this paper, the design of the new model as well as the prototype manufacturing schedule are presented in more detail.

  10. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    PubMed

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  11. Ionization of EPA Contaminants in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization

    NASA Astrophysics Data System (ADS)

    Kauppila, Tiina J.; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  12. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    PubMed

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI. PMID:25828352

  13. Biological Effects of Ionizing Radiation

    DOE R&D Accomplishments Database

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  14. Mass analyzed threshold ionization spectroscopy of 4-aminobenzonitrile cation

    NASA Astrophysics Data System (ADS)

    Huang, L. C. L.; Lin, J. L.; Tzeng, W. B.

    2000-11-01

    Mass analyzed threshold ionization (MATI) and two-color resonant two-photon ionization (R2PI) methods were used to investigate the ionic properties of 4-aminobenzonitrile (4-ABN). The adiabatic ionization energy of this molecule was determined to be 66 493±4 cm -1 by the MATI spectroscopy and 66 494±7 cm -1 by the two-color R2PI spectroscopy. The active vibrations of the 4-ABN cation include the in-plane ring deformation, CC stretching, C-CN stretching, and CH bending motions. The present experimental results are well supported by our ab initio and density functional theory calculations.

  15. Ionization sources and mass analyzers in MS imaging.

    PubMed

    Tsai, Yu-Hsuan; Menger, Robert F; Drexler, Dieter M; Yost, Richard A; Garrett, Timothy J

    2015-01-01

    Drug absorption, distribution, metabolism, excretion and toxicology study is one important step in drug discovery and development. MS imaging has become one of the popular methods in this field. Here, selected ionization methods such as matrix-assisted laser desorption/ionization, secondary ion MS and desorption electrospray ionization have been briefly discussed. To differentiate drug and drug metabolites from endogenous compounds present in the biological system, exact mass and/or tandem MS is necessary. As a result, mass analyzers such as time-of-flight, Fourier transform ion cyclotron resonance or Orbitrap are often the method of choice and are briefly introduced. PMID:26511148

  16. Argonne CW Linac (ACWL)—legacy from SDI and opportunities for the future

    NASA Astrophysics Data System (ADS)

    McMichael, G. E.; Yule, T. J.

    1995-09-01

    The former Strategic Defense Initiative Organization (SDIO) invested significant resources over a 6-year period to develop and build an accelerator to demonstrate the launching of a cw beam with characteristics suitable for a space-based Neutral Particle Beam (NPB) system. This accelerator, the CWDD (Continuous Wave Deuterium Demonstrator) accelerator, was designed to accelerate 80 mA cw of D- to 7.5 MeV. A considerable amount of hardware was constructed and installed in the Argonne-based facility, and major performance milestones were achieved before program funding from the Department of Defense ended in October 1993. Existing assets have been turned over to Argonne. Assets include a fully functional 200 kV cw D- injector, a cw RFQ that has been tuned, leak checked and aligned, beam lines and a high-power beam stop, all installed in a shielded vault with appropriate safety and interlock systems. In addition, there are two high power (1 MW) cw rf amplifiers and all the ancillary power, cooling and control systems required for a high-power accelerator system. The SDI mission required that the CWDD accelerator structures operate at cryogenic temperatures (26K), a requirement that placed severe limitations on operating period (CWDD would have provided 20 seconds of cw beam every 90 minutes). However, the accelerator structures were designed for full-power rf operation with water cooling and ACWL (Argonne Continuous Wave Linac), the new name for CWDD in its water-cooled, positive-ion configuration, will be able to operate continuously. Project status and achievements will be reviewed. Preliminary design of a proton conversion for the RFQ, and other proposals for turning ACWL into a testbed for cw-linac engineering, will be discussed.

  17. Unstable resonators with excited converging wave

    SciTech Connect

    Hodgson, N. ); Weber, H. )

    1990-04-01

    This paper reports the properties of unstable resonators with an additional mirror inside or outside the resonator investigated, both experimentally and theoretically. The additional mirror excites the converging wave, and by this, output coupling is decreased without affecting beam quality. Experiments were performed with a pulsed Nd:YAG system. The theoretical model was based on the coupled Kirchhoff integrals and solved numerically. Agreement between theory and experiments indicates that this kind of resonator provides high focusability and maximum extraction efficiency simultaneously, even with low-gain media. This enables one to apply unstable resonators to solid-state lasers with low small-signal gain, like alexandrite or CW-pumped Nd:YAG.

  18. Diffuse, Warm Ionized Gas

    NASA Astrophysics Data System (ADS)

    Haffner, L. M.

    2002-05-01

    Over the past decade, new high-sensitivity observations have significantly advanced our knowledge of the diffuse, ionized gas in spiral galaxies. This component of the interstellar medium, often referred to as Warm Ionized Medium (WIM) or Diffuse Ionized Gas (DIG), plays an important role in the complex stellar-interstellar matter and energy cycle. In examining the distribution and physical properties of this gas, we learn not only about the conditions of the medium but also about processes providing heating and ionization in the halos of spiral galaxies. For the Milky Way, three new Hα surveys are available providing large sky coverage, arc-minute spatial resolution, and the ability to kinematically resolve this prominent optical emission line. These new, global views show that the Warm Ionized Medium of the Galaxy is ubiquitous as previously suspected, is rich with filamentary structure down to current resolution limits, and can be traced into the halo at large distances from the Galactic plane. Observations of additional optical emission lines are beginning to probe the physical conditions of the WIM. Early results suggest variations in the temperature and ionization state of the gas which are not adequately explained by Lyman continuum stellar photoionization alone. In parallel with this intensive work in the Milky Way have been numerous studies about the diffuse, ionized gas in other spiral galaxies. Here, deep, face-on spiral investigations provide some of the best maps of the global DIG distribution in a galaxy and begin to allow a probe of the local link between star formation and the powering of ionized gas. In addition, ionized gas has been traced out to impressive distances (z > 3 kpc) in edge-on spirals, revealing out large-scale changes in the physical conditions and kinematics of galactic halos.

  19. Abnormal ionization in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  20. Study of potassium DPAL operation in pulsed and CW mode

    NASA Astrophysics Data System (ADS)

    Zhdanov, Boris V.; Rotondaro, Matthew D.; Schaffer, Michael K.; Knize, Randall J.

    2014-10-01

    This paper presents the results of our experiments on development of the efficient hydrocarbon free Diode Pumped Alkali Laser based on potassium vapor buffered by He gas at 600 Torr. We studied the performance of this laser operating in pulsed mode with pulses up to 5 ms long at different pulse energies and cell temperatures. A slope efficiency of more than 50% was demonstrated with total optical efficiency about 30% for the pump pulses with duration about 30 μs. For the longer pump pulses the DPAL efficiency degraded in time with a characteristic time in the range from 0.5 ms to 4.5 ms depending on the pump pulse energy and cell temperature. The recorded spectrum of the side fluorescence indicates that multi-photon excitation, energy pooling collisions and ionization may be strong candidates for explaining the observed performance degradation.

  1. Single dose toxicity study of IRDye 800CW in Sprague-Dawley rats

    NASA Astrophysics Data System (ADS)

    Marshall, Milton V.; Draney, Daniel; Sevick-Muraca, Eva M.; Olive, D. Michael

    2010-02-01

    Fluorophore-labeled contrast imaging agents are moving toward clinical use as aids in nodal staging and intraoperative resection of tumors. Near-infrared fluorophores with defined toxicity properties will be needed before these agents can be translated to the clinic. The near-infrared dye IRDye 800CW is frequently used in its N-hydroxysuccinamide (NHS) ester form for labeling these agents. Following conjugation or breakdown of a labeled ligand, excess NHS ester is converted to the carboxylate form. We report here the results of a preliminary toxicity study on IRDye 800CW carboxylate in preparation for its use as a labeling moiety for targeted contrast agents. Male and female Sprague Dawley rats were given a single intravenous or intradermal administration of IRDye 800CW carboxylate; indocyanine green was used as a comparative control. Following administration of varying doses of either the dyes or saline, animals were observed for up to fourteen days during which time, hematological, clinical chemistry, enzymological, and histological testing was performed on animal subgroups. Under the conditions tested, a single administration of IRDye 800CW carboxylate intravenously at dose levels of 1, 5 and 20 mg/kg or 20 mg/kg intradermally produced no pathological evidence of toxicity. A dose of 20 mg/kg was identified as the NOAEL (no observed adverse effect level) following IV or ID routes of administration of IRDye 800CW.

  2. Study of human leukocyte antigen-cw in Egyptian patients with vitiligo.

    PubMed

    Hassab El Naby, Hussein M; Alnaggar, Mohamed R; Abdelhamid, Mahmoud F; Alsaid, Khadiga; Al Shawadfy, Eslam M; Elsaie, Mohamed L

    2015-04-01

    Human leukocyte antigen (HLA) antigens vary considerably in different racial groups, and an analysis of results from several geographical locations suggests that vitiligo appears to be associated with different HLA antigens in different groups. The aim of this work was to assess the association of HLA-Cw with vitiligo in the Egyptian population. Forty unrelated patients with nonsegmental vitiligo and 20 matched controls were selected. A polymerase chain reaction sequence specific primer (PCR-SSP) method was used to determine HLA DNA typing. There was a statistically significant difference in the association of HLA-Cw6 with vitiligo in the 2 studied groups. A comparatively increased number of patients showed HLA-Cw2 and HLA-Cw7 (13.64%). However, there were no statistically significant differences. To the best of our knowledge, this is the first molecular study of HLA typing in Egyptian patients with vitiligo. Our findings are in agreement with earlier studies that reported statistically increased frequencies for allele of HLA-Cw6 in Northern Italian, Kuwaiti, Chinese Han, and Saudi populations (45.45%, P<.05).

  3. [Frequency of HLA-A, HLA-B and HLA-Cw antigens in the Slovak population].

    PubMed

    Kralovicova, J; Kusikova, M; Buc, M; Holomanova, D; Sakalova, A

    2000-01-01

    Results on HLA-A, -B and -Cw antigen frequencies in the Slovak population are presented. HLA-A, -B, -Cw antigens were determined in 654 healthy unrelated individuals. The highest frequency was observed for the antigens HLA-A2, -A1; HLA-B12, -B35, and HLA-Cw8. The least frequent antigens were HLA-A34, -A36, HLA-B58, -B67, -B70, -B77, and HLA-Cw8. The results were compared with those of the previous study and with those of Czech, Austrian and Hungarian populations. No statistically significant differences were observed. (Tab. 5, Fig. 2, Ref. 9.)

  4. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers. PMID:26486514

  5. "Magic" Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  6. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  7. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  8. Exit channels of autoionization resonances in atoms

    SciTech Connect

    Krause, M.O.

    1985-01-01

    In many-electron atoms with open shells strong autoionization resonances occur when an electron from an inner, weakly bound subshell is excited. Usually, the resonance state lies above several ionization thresholds and, hence, will decay into more than one exit or continuum channel. Several cases are discussed in which the resonance state is induced by synchrotron radiation, and the exit channels are differentiated and characterized by the analysis of the ejected electrons.

  9. Design considerations in achieving 1 MW CW operation with a whispering-gallery-mode gyrotron

    SciTech Connect

    Felch, K.; Feinstein, J.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Pirkle, D.; Zitelli, L. )

    1989-09-01

    Varian is developing high-power, CW gyrotrons at frequencies in the range 100 GHz to 150 GHz, for use in electron cyclotron heating applications. Early test vehicles have utilized a TE{sub 15,2,1} interaction cavity, have achieved short-pulse power levels of 820 kW and average power levels of 80 kW at 140 GHz. Present tests are aimed at reaching 400 kW under CW operating conditions and up to 1 MW for short pulse durations. Work is also underway on modifications to the present design that will enable power levels of up to 1 MW CW to be achieved. 7 refs., 2 figs.

  10. CW-THz image contrast enhancement using wavelet transform and Retinex

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Zhang, Min; Hu, Qi-fan; Huang, Ying-Xue; Liang, Hua-Wei

    2015-10-01

    To enhance continuous wave terahertz (CW-THz) scanning images contrast and denoising, a method based on wavelet transform and Retinex theory was proposed. In this paper, the factors affecting the quality of CW-THz images were analysed. Second, an approach of combination of the discrete wavelet transform (DWT) and a designed nonlinear function in wavelet domain for the purpose of contrast enhancing was applied. Then, we combine the Retinex algorithm for further contrast enhancement. To evaluate the effectiveness of the proposed method in qualitative and quantitative, it was compared with the adaptive histogram equalization method, the homomorphic filtering method and the SSR(Single-Scale-Retinex) method. Experimental results demonstrated that the presented algorithm can effectively enhance the contrast of CW-THZ image and obtain better visual effect.

  11. Efficacy of photodynamic inactivation against Pseudomonas aeruginosa with pulsed light and CW light excitation

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tohru; Sato, Shunichi; Kawauchi, Satoko; Terakawa, Mitsuhiro; Shinomiya, Nariyoshi; Saitoh, Daizoh; Ashida, Hiroshi; Obara, Minoru

    2006-02-01

    We compared methylene blue (MB)-mediated photobactericidal efficacies against Pseudomonas aeruginosa when using nanosecond pulsed light and CW light. In the intensity range of 10-200 mW/cm2, there was no significant difference between two cases, while photobactericidal efficacy with nanosecond pulsed light was significantly lower than that with CW light at an intensity of 250 mW/cm2. This is attributable to the saturated absorption of MB molecules due to high peak intensity of nanosecond pulsed light. On the basis of these results, we estimated the depth dependence of bacterial killing, showing that in the skin tissue region deeper than 1.5 mm, photobactericidal efficacy with nanosecond pulsed light was higher than that with CW light. This suggests that the advantage of using high-peak-intensity pulsed light for deep tissue treatment.

  12. The experimental study of a CW 1080 nm multi-point pump fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xuexia; Ge, Tingwu; Ding, Xing; Tan, Qirui; Wang, Zhiyong

    2016-07-01

    In this paper, we report on a CW 1080 nm fiber laser cascaded-pumped by a CW 975 nm diode laser. The fiber used in the experiment has a core diameter of 20 μm (NA  =  0.06), inner clad of 400 μm (NA  =  0.46), and an absorption coefficient of about 1.26 dB m-1 at 975 nm. An output power of 780 W with an optical conversion efficiency of 71% has been achieved at a pump light of 1.1 kW. To the best of our knowledge, this is the first time that a 1080 nm CW fiber laser has used a cascaded-pump coupler.

  13. Installation of a cw radiofrequency quadrupole accelerator at Los Alamos National Laboratory

    SciTech Connect

    Schneider, J.D.; Bolme, J.; Brown, V.

    1994-09-01

    Chalk River Laboratories (CRL) has had a long history of cw proton beam development for production of intense neutron sources and fissile fuel breeders. In 1986 CRL and Los Alamos National Laboratory (LANL) entered into a collaborative effort to establish a base technologies program for the development of a cw radiofrequency quadrupole (RFQ). The initial cw RFQ design had 50-keV proton injection energy with 600-keV output energy. The 75-mA design current at 600-keV beam energy was obtained in 1990. Subsequently, the RFQ output energy was increased to 1250 keV by replacing the RFQ vanes, still maintaining the 75-m A design current. A new 250-kW cw klystrode rf power source at 267-MHz was installed at CRL. By April of 1993, 55-mA proton beams had been accelerated to 1250 keV. Concurrent developments were taking place on proton source development and on 50-keV low-energy beam transport (LEBT) systems. Development of a dc, high-proton fraction ({ge} 70%) microwave ion source led to utilization of a single-solenoid RFQ direct injection scheme. It was decided to continue this cw RFQ demonstration project at Los Alamos when the CRL project was terminated in April 1993. The LANL goals are to find the current limit of the 1250-keV RFQ, better understand the beam transport properties through the single-solenoid focusing LEBT, continue the application of the cw klystrode tube technology to accelerators, and develop a two-solenoid LEBT which could be the front end of an Accelerator-Driven Transmutation Technologies (ADTT) linear accelerator.

  14. Fuel cell with ionization membrane

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2007-01-01

    A fuel cell is disclosed comprising an ionization membrane having at least one area through which gas is passed, and which ionizes the gas passing therethrough, and a cathode for receiving the ions generated by the ionization membrane. The ionization membrane may include one or more openings in the membrane with electrodes that are located closer than a mean free path of molecules within the gas to be ionized. Methods of manufacture are also provided.

  15. Theoretical study of cw to short pulse conversion in an active cw-injected ring cavity with a Yb3+:YAG amplifier.

    PubMed

    Huang, Zhiyun; Bourdet, Gilbert L

    2007-05-10

    The short laser pulse generated from an active cw-injected ring cavity with Yb3+:YAG crystal, which is treated as the homogeneously broadened amplifier, is studied theoretically. Based on the derived results, the impacts of the amplifier length, the seeding laser intensity and frequency, the pump intensity, the efficiency of the acousto-optic modulator (AOM), and the frequency shift generated by the AOM on the performance of the laser pulse are analyzed. PMID:17446920

  16. Effect of scanned quasi-cw CO2 laser irradiation on tissue thermal damage

    NASA Astrophysics Data System (ADS)

    Domankevitz, Yacov; Bua, Dominic; Chung, Jina; Hanel, Edward; Silver, Geoffrey; Nishioka, Norman S.

    1994-08-01

    Residual thermal damage produced by a scanned quasi cw CO2 laser was measured in pig skin. The effects of scan speed on thermal damage distribution for laser dwell times ranging between 1 and 150 msec were examined. Significantly larger thermal damage zones were produced along the crater wall for laser dwell times longer than 50 msec. Thermal damage along the crater base was constant independent of dwell time. The preliminary experimental results suggest that quasi cw CO2 can consistently produce less than 200 micrometers zones of thermal damage if laser parameters are carefully chosen.

  17. Admittance Test and Conceptual Study of a CW Positron Source for CEBAF

    SciTech Connect

    Golge, Serkan; Hyde, Charles E.; Freyberger, Arne

    2009-09-02

    A conceptual study of a Continuous Wave (CW) positron production is presented in this paper. The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLAB) operates with a CW electron beam with a well-defined emittance, time structure and energy spread. Positrons created via bremsstrahlung photons in a high-Z target emerge with a large emittance compared to incoming electron beam. An admittance study has been performed at CEBAF to estimate the maximum beam phase space area that can be transported in the LINAC and in the Arcs. A positron source is described utilizing the CEBAF injector electron beam, and directly injecting the positrons into the CEBAF LINAC.

  18. Modulated Sine Waves for Differential Absorption Measurements Using a CW Laser System

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor); Lin, Bing (Inventor); Nehrir, Amin R. (Inventor)

    2015-01-01

    A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

  19. Diode pumped CW and passively Q-switched Nd:LGGG laser at 1062 nm

    NASA Astrophysics Data System (ADS)

    Yang, H.; Jia, Z. T.; Zhang, B. T.; He, J. L.; Liu, S. D.; Yang, Y.; Tao, X. T.

    2012-05-01

    We report a Nd:LGGG laser at 1062 nm in the operations of the continuous-wave (CW) and passively Q-switching. The maximum CW output power of 5.62 W was obtained, corresponding to an optical-to-optical conversion efficiency of 49.0% and slope efficiency of 55.9%. By using Cr4+:YAG with initial transmission of 94% as the saturable absorber, for the first time, we got the maximum passively Q-switched output power of 1.21 W, accompanied with a highest pulse repetition rate of 27.1 kHz and a shortest pulse width of 9.1 ns.

  20. Evaluation of a Novel Approach for Peptide Sequencing: Laser-induced Acoustic Desorption Combined with P(OCH3)2+ Chemical Ionization and Collision-activated Dissociation in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Somuramasami, Jayalakshmi; Kenttämaa, Hilkka I.

    2007-01-01

    A novel mass spectrometric method has been developed for obtaining sequence information on small peptides. The peptides are desorbed as intact neutral molecules into a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) by means of laser-induced acoustic desorption (LIAD). Reactions of the neutral peptides with the dimethoxyphosphenium ion, P(OCH3)2+, occur predominantly by addition of the peptide to P(OCH3)2+ followed by the loss of two methanol molecules, thus yielding product ions with the composition (peptide + P − 2H)+. Upon sustained off-resonance irradiation for collision-activated dissociation (SORI-CAD), the (peptide + P − 2H)+ ions undergo successive losses of CO and NH = CHR or H2O, CO, and NH = CHR to yield sequence-related fragment ions in addition to the regular an- and bn-type ions. Under the same conditions, SORI-CAD of the analogous protonated peptides predominantly yields the regular an- and bn-type ions. The mechanisms of the reactions of peptides with P(OCH3)2+ and the dissociation of the (peptide + P − 2H)+ ions were examined by using model peptides and molecular orbital calculations. PMID:17157527

  1. Laser-Induced Ionization Efficiency Enhancement On A Filament For Thermal Ionization Mass Spectrometry

    SciTech Connect

    Siegfried, M.

    2015-10-14

    The evaluation of trace Uranium and Plutonium isotope ratios for nanogram to femtogram material quantities is a vital tool for nuclear counter-proliferation and safeguard activities. Thermal Ionization Mass Spectrometry (TIMS) is generally accepted as the state of the art technology for highly accurate and ultra-trace measurements of these actinide ratios. However, the very low TIMS ionization yield (typically less than 1%) leaves much room for improvement. Enhanced ionization of Nd and Sm from a TIMS filament was demonstrated using wavelength resonance with a nanosecond (pulse width) laser operating at 10 Hz when light was directed toward the filament.1 For this study, femtosecond and picosecond laser capabilities were to be employed to study the dissociation and ionization mechanisms of actinides/lanthanides and measure the enhanced ionization of the metal of interest. Since the underlying chemistry of the actinide/lanthanide carbides produced and dissociated on a TIMS filament is not well understood, the experimental parameters affecting the photodissociation and photoionization with one and two laser beams were to be investigated.

  2. Upper Hybrid Effects in Artificial Ionization

    NASA Astrophysics Data System (ADS)

    Papadopoulos, K.; Eliasson, B. E.

    2014-12-01

    A most fascinating result of recent ionospheric experiments has been the discovery of artificial ionization by Pedersen et al. (GRL, 37, L02106, 2010). The Artificial Ionospheric Layers (AIL) were the result of F-region O-mode HF irradiation using the HAARP ionospheric heater operating at 3.6 MW power. As demonstrated by Eliasson et al. (JGR, 117, A10321, 2012) the physics controlling the observed phenomenon and its threshold can be summarized as: " Collisional ionization due to high energy (~ 20 eV) electron tails generated by the interaction of strong Langmuir turbulence with plasma heated at the upper hybrid resonance and transported at the reflection height". The objective of the current presentation is to explore the role of the upper hybrid heating in the formation of AIL and its implications to future experiments involving HF heaters operating in middle and equatorial latitudes.

  3. Non-adiabatic, superfast passage to resonance: an alternative to pulsed fourier transform for absorption line shapes

    NASA Astrophysics Data System (ADS)

    Segel, S. L.; Creel, R. B.; Torgeson, D. R.

    1983-12-01

    We describe the theory, practice and experimental results of a continuous wave (CW) resonance technique which we call non-adiabatic superfast passage (NASP). NASP signal to noise per unit time (SNT) is better than pulsed Fourier transform spectrometers (PFTS) and far better than the conventional CW slow passage NMR using field modulation, lock-in amplifiers and signal averaging techniques. It is most useful in situations of long spin-lattice relaxation time and particularly those cases where the line shape is composed of narrow and broad components, as in a typical second-order quadrupolar perturbed magnetic resonance line shape.

  4. Testing of detector papers with CW liquid-agent droplets of known diameter. Droplets generator, calibration, and procedures. Technical note

    SciTech Connect

    Thoraval, D.; Bovenkamp, J.W.; Bets, R.W.; Preston, J.M.; Hart, L.G.

    1986-01-01

    The droplet generator used at DREO to test the color-producing ability of detector papers with CW-agent droplets of known diameter is described. The calibration of the equipment, the droplet size consistency and the procedure used to test the CW-agent-detector papers are discussed.

  5. Combined CW ring single-frequency Ti:sapphire/dye laser for atom cooling and high-precision spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobtsev, Sergey; Baraulya, Vladimir; Lunin, Vladimir

    2007-04-01

    Presented in the work are the results of the development of a new combined CW ring single-frequency laser with universal design that allows efficient use as the active medium of both a Ti:Sapphire crystal and a dye jet. For the first time such combination has been implemented in a horizontal resonator configuration that offers an improvement of stability in the position of optical elements and more convenient operation. The short-term line width without the frequency stabilisation is less than 5 MHz (Ti:Sapphire) and < 10 MHz (Dye); with the frequency stabilisation to a specially designed thermo-stabilised reference interferometer with high finesse, the line width is less than 10 kHz (Ti:Sapphire) and 90 kHz (Dye), output frequency drift being less than 25 MHz/hour. The total working spectral range of the combined laser stretches from 550 to 1000 nm (550-770 nm for the Dye and 695-1000 nm for Ti:Sapphire) when pumped with 532/515-nm radiation. The maximum output power with a 10-W pump exceeds 2 W for the Ti:Sapphire configuration and is > 1 .5 W for the Dye one.

  6. CFD assisted simulation of temperature distribution and laser power in pulsed and CW pumped static gas DPALs

    NASA Astrophysics Data System (ADS)

    Waichman, Karol; Barmashenko, Boris D.; Rosenwaks, Salman

    2015-10-01

    An analysis of radiation, kinetic and fluid dynamic processes in diode pumped alkali lasers (DPALs) is reported. The analysis is based on a three-dimensional, time-dependent computational fluid dynamics (3D CFD) model. The CFD code which solves the gas conservation equations includes effects of natural convection and temperature diffusion of the species in the DPAL mixture. The gas flow conservation equations are coupled to the equations for DPAL kinetics and to the Beer-Lambert equations for pump and laser beams propagation. The DPAL kinetic processes in the Cs/CH4 (K/He) gas mixtures considered involve the three low energy levels, (1) n2S1/2, (2) n2P3/2 and (3) n2P1/2 (where n=4,6 for K and Cs, respectively), three excited alkali states and two alkali ionic states. Using the CFD model, the gas flow pattern and spatial distributions of the pump and laser intensities in the resonator were calculated for end-pumped CW and pulsed Cs and K DPALs. The DPAL power and medium temperature were calculated as a function of pump power and pump pulse duration. The CFD model results were compared to experimental results of Cs and K DPALs.

  7. CW lasing in Yb{sup 3+} : GGG crystals pumped at 0.925 {mu}m

    SciTech Connect

    Belovolov, A M; Belovolov, M I; Dianov, Evgenii M; Dudin, V V; Timoshechkin, M I E-mail: dianov@fo.gpi.r

    2006-07-31

    Single-mode cw lasing was obtained for the first time in Yb{sup 3+} : GGG crystals at room temperature at 1.030 and 1.037 {mu}m upon pumping Yb{sup 3+} ions by a 0.925-{mu}m neodymium-doped fibre laser. Lasing was observed at the transitions between the lower Stark sublevel of the {sup 2}F{sub 5/2} level and the upper Stark sublevels of the {sup 2}F{sub 7/2} ground state of Yb{sup 3+} ions. The study of lasing characteristic showed that lasing occurs according to the four-level scheme. The lasing threshold with respect to the absorbed power was 85 mW and the slope lasing efficiency was 20%. Upon 1.7-W pumping, the output power of 310 mW was achieved with the output resonator mirror with the transmission coefficient of 1%. The effective cross section of the lasing transition was 0.9x10{sup -20} cm{sup 2}. (special issue devoted to the 90th anniversary of a.m. prokhorov)

  8. Ambient ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lebedev, A. T.

    2015-07-01

    Ambient ionization mass spectrometry emerged as a new scientific discipline only about ten years ago. A considerable body of information has been reported since that time. Keeping the sensitivity, performance and informativity of classical mass spectrometry methods, the new approach made it possible to eliminate laborious sample preparation procedures and triggered the development of miniaturized instruments to work directly in the field. The review concerns the theoretical foundations and design of ambient ionization methods. Their advantages and drawbacks, as well as prospects for application in chemistry, biology, medicine, environmetal analysis, etc., are discussed. The bibliography includes 194 references.

  9. Determination of the first ionization potential of technetium

    SciTech Connect

    Mattolat, C.; Gottwald, T.; Raeder, S.; Rothe, S.; Schwellnus, F.; Wendt, K.; Thoerle-Pospiech, P.; Trautmann, N.

    2010-05-15

    The first ionization potential (IP) of technetium (Tc) has been determined by evaluating Rydberg convergences toward the first ionization potential as well as toward two low-lying excited states of the singly charged Tc ion. The Rydberg states were excited and detected by applying multiphoton resonance ionization mass spectrometry (RIMS) on the long-lived isotope {sup 99g}Tc using a three-color excitation scheme. The observed Rydberg convergences yield a result for the first ionization potential of Tc V{sub IP}(Tc)=7.119380(32) eV. This precise value for V{sub IP}(Tc) is somewhat lower than the so far published data of 7.23 eV or 7.28 eV, dating back to the 1950s.

  10. Class-Wide Function-Related Intervention Teams "CW-FIT" Efficacy Trial Outcomes

    ERIC Educational Resources Information Center

    Kamps, Debra; Wills, Howard; Dawson-Bannister, Harriett; Heitzman-Powell, Linda; Kottwitz, Esther; Hansen, Blake; Fleming, Kandace

    2015-01-01

    The purpose of the study was to determine the efficacy of the Class-Wide Function-Related Intervention Teams (CW-FIT) program for improving students' on-task behavior, and increasing teacher recognition of appropriate behavior. The intervention is a group contingency classroom management program consisting of teaching and reinforcing appropriate…

  11. Method for generating high-energy and high repetition rate laser pulses from CW amplifiers

    DOEpatents

    Zhang, Shukui

    2013-06-18

    A method for obtaining high-energy, high repetition rate laser pulses simultaneously using continuous wave (CW) amplifiers is described. The method provides for generating micro-joule level energy in pico-second laser pulses at Mega-hertz repetition rates.

  12. Development of a high average power, CW, MM-wave FEL

    SciTech Connect

    Ramian, G.

    1995-12-31

    Important operational attributes of FELs remain to be demonstrated including high average power and single-frequency, extremely narrow-linewidth lasing. An FEL specifically designed to achieve these goals for scientific research applications is currently under construction. Its most salient feature is operation in a continuous-wave (CW) mode with an electrostatically generated, high-current, recirculating, DC electron beam.

  13. Use of Self-Management with the CW-FIT Group Contingency Program

    ERIC Educational Resources Information Center

    Kamps, Debra; Conklin, Carl; Wills, Howard

    2015-01-01

    The purpose of the study was to determine the effects of self-management as a tier two enhancement to the group contingency intervention, Class-Wide Function-related Intervention Teams Program (CW-FIT). Two classrooms, first and fourth grade, and two students in each of the classrooms participated in the intervention. The group contingency…

  14. Noise amplitude measurements of single-mode CW lasers at radio frequencies

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Hillard, M. E., Jr.

    1992-01-01

    This letter presents the results of noise measurements for a variety of single-longitudinal-mode CW lasers (Ar/+/, standing-wave-dye, and ring-dye) that are commercially available. A quantitative comparison of the total output power fluctuations detected over the 7-300 MHz region (3 dB points) is presented.

  15. Red-light-emitting laser diodes operating CW at room temperature

    NASA Technical Reports Server (NTRS)

    Kressel, H.; Hawrylo, F. Z.

    1976-01-01

    Heterojunction laser diodes of AlGaAs have been prepared with threshold current densities substantially below those previously achieved at room temperature in the 7200-8000-A spectral range. These devices operate continuously with simple oxide-isolated stripe contacts to 7400 A, which extends CW operation into the visible (red) portion of the spectrum.

  16. Characterization of High-power Quasi-cw Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Vasilyev, Aleksey; Troupaki, Elisavet; Allan, Graham R.; Kashem, Nasir B.

    2005-01-01

    NASA s requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  17. The HW resonators in Jülich

    NASA Astrophysics Data System (ADS)

    Stassen, R.; Eichhorn, R.; Esser, F. M.; Laatsch, B.; Schug, G.; Singer, H.

    2006-07-01

    Within the design of a new injector for the cooler synchrotron COSY, a linac option based on pulsed superconducting half-wave resonators (HWR) has been investigated. Two prototypes of the HWRs at 160 MHz were built by different manufacturers. We will present measurements for CW as well as pulsed operation to characterize RF performance and mechanical behavior of the two cavities. Whereas the slight differences in fabrication did not affect the electromagnetic results, the mechanical properties (mechanical eigenresonances, Lorentz-force detuning) significantly differed. To operate the cavities, ancillary systems (coupler, tuner, RF control) were designed and tested; the results of those will be summarized.

  18. Niobium resonator development for high-brightness ion beam acceleration

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Roche, C.T.

    1990-01-01

    Two niobium resonant cavities for high-brightness ion beam acceleration have been constructed and tested. The first was based on a coaxial quarter-wave geometry and was optimized for phase velocity {beta}{sub o} = 0.15. This cavity, which resonates at 400 MHz in the fundamental mode, operated at an average (wall-to-wall) accelerating gradient of 12.9 MV/m under continuous-wave (cw) fields. At this gradient, a cavity Q of 1.4 {times} 10{sup 8} was measured. The second was based on a coaxial half-wave geometry and was optimized for {beta}{sub o} = 0.12. This cavity, which resonates at 355 MHz in the fundamental mode, operated at an average accelerating gradient of 18.0 MV/m under cw fields. This is the highest average accelerating gradient achieved to date in low-velocity structures designed for cw operation. At this gradient, a cavity Q of 1.2 {times} 10{sup 8} was measured.

  19. Possibilities of improving the performance of an autonomous cw chemical DF laser by replacing the slot nozzles by the ramp ones in the nozzle array

    SciTech Connect

    Bashkin, A S; Gurov, L V; Kurdyukov, M V

    2011-08-31

    The results of a comparative numerical study of the performance of an autonomous cw chemical DF laser are obtained by simulating the processes in the nozzles and laser cavity where several configurations of slot and ramp nozzle arrays are employed. Three-dimensional Navier-Stokes equations solved with the Ansys CFX software are used to describe the reacting multicomponent flow in the nozzles and laser cavity. To investigate lasing characteristics, a supplementary code is developed and is used to calculate the radiation intensity in the Fabry-Perot resonator, taking into account its nonuniform distribution along the aperture width and height. It is shown that the use of the nozzle array consisting of ramp nozzles, which, in contrast to the slot nozzles, provide enhanced mixing of the reactants makes it possible to improve the laser performance in the case of a high-pressure (more than 15 Torr) active medium. (control of radiation parameters)

  20. Alkali ionization detector

    DOEpatents

    Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

    1982-01-01

    A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

  1. Identification of active compounds and their metabolites by high-performance liquid chromatography/electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry from Xiao-xu-ming decoction (XXMD).

    PubMed

    Wang, Yilin; Ding, Chunguang; Du, Kehe; Xiao, Yao; Wu, Caisheng; Zhang, Jinlan; Qin, Hailin; Du, Guanhua

    2009-09-01

    Xiao-xu-ming decoction (XXMD) prescription is a traditional Chinese prescription that has been widely used to treat theoplegia and the sequela of theoplegia. Modern pharmacological research has also indicated that the active fraction from XXMD is able to treat cardiovascular diseases and Alzheimer's disease. In the study reported here, high-performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICR-MS) was developed to identify active compounds and their metabolites after oral administration of active fraction from Xiao-xu-ming decoction to rats, using parent mass list triggered data-dependent multiple-stage mass analysis at a resolving power of 100,000 in the external calibration mode. The mass accuracies obtained for full-scan MS were within 2 ppm in most cases. Fifteen constituents were identified in the active fraction from XXMD and the biological samples of rats. The fragmentation behaviors of these constituents were summarized which would be helpful for structural characterization. The profiles of the constituents in the active fraction and biological samples of rats were obtained which provided us with much information for a better understanding of the chemical basis of the pharmacologic actions of XXMD.

  2. Optics for Phase Ionization Cooling of Muon Beams

    SciTech Connect

    R.P. Johnson; S.A. Bogacz; Y.S. Derbenev

    2006-06-26

    The realization of a muon collider requires a reduction of the 6D normalized emittance of an initially generated muon beam by a factor of more than 106. Analytical and simulation studies of 6D muon beam ionization cooling in a helical channel filled with pressurized gas or liquid hydrogen absorber indicate that a factor of 106 is possible. Further reduction of the normalized 4D transverse emittance by an additional two orders of magnitude is envisioned using Parametric-resonance Ionization Cooling (PIC). To realize the phase shrinkage effect in the parametric resonance method, one needs to design a focusing channel free of chromatic and spherical aberrations. We report results of our study of a concept of an aberration-free wiggler transport line with an alternating dispersion function. Resonant beam focusing at thin beryllium wedge absorber plates positioned near zero dispersion points then provides the predicted PIC effect.

  3. Modulated voltage metastable ionization detector

    NASA Technical Reports Server (NTRS)

    Carle, G. C.; Kojiro, D. R.; Humphrey, D. E. (Inventor)

    1985-01-01

    The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level. When the detected current from the metastable ionization detector increases above a predetermined threshold level, a voltage control circuit is activated which turns on a high voltage transistor which acts to reduce the ionization potential. The ionization potential applied to the metastable ionization detector is then varied so as to maintain the detected signal level constant. The variation in ionization potential is now related to the concentration of the constituent and a representative amplitude is applied to another input of said strip chart recorder.

  4. Structural characterization of native high-methoxylated pectin using nuclear magnetic resonance spectroscopy and ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Comparative use of 2,5-dihydroxybenzoic acid and nor-harmane as UV-MALDI matrices.

    PubMed

    Monge, María Eugenia; Negri, R Martín; Kolender, Adriana A; Erra-Balsells, Rosa

    2007-01-01

    The successful analysis by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) of native and hydrolyzed high-methoxylated pectin samples is described. In order to find the optimal conditions for UV-MALDI-TOF MS analysis several experimental variables were studied such as: different UV-MALDI matrices (nor-harmane, 2,5-dihydroxybenzoic acid), sample preparation methods (mixture, sandwich), inorganic salt addition (doping salts, NaCl, KCl, NH(4)Cl), ion mode (positive, negative), linear and reflectron mode, etc. nor-Harmane has never been used as a UV-MALDI matrix for the analysis of pectins but its use avoids pre-treatment of the sample, such as an enzymatic digestion or an acid hydrolysis, and there is no need to add salts, making the analysis easier and faster. This study suggested an alternative way of analyzing native high-methoxylated pectins, with UV-MALDI-TOF MS, by using nor-harmane as the matrix in negative ion mode. The analysis by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy of the native and hydrolyzed pectin is also briefly described.

  5. Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of bromobenzene and its perdeuterated isotopologue: Assignment of the vibrations of the S{sub 0}, S{sub 1}, and D{sub 0}{sup +} states of bromobenzene and the S{sub 0} and D{sub 0}{sup +} states of iodobenzene

    SciTech Connect

    Andrejeva, Anna; Tuttle, William D.; Harris, Joe P.; Wright, Timothy G.

    2015-12-28

    We report vibrationally resolved spectra of the S{sub 1}←S{sub 0} transition of bromobenzene using resonance-enhanced multiphoton ionization spectroscopy. We study bromobenzene-h{sub 5} as well as its perdeuterated isotopologue, bromobenzene-d{sub 5}. The form of the vibrational modes between the isotopologues and also between the S{sub 0} and S{sub 1} electronic states is discussed for each species, allowing assignment of the bands to be achieved and the activity between states and isotopologues to be established. Vibrational bands are assigned utilizing quantum chemical calculations, previous experimental results, and isotopic shifts. Previous work and assignments of the S{sub 1} spectra are discussed. Additionally, the vibrations in the ground state cation, D{sub 0}{sup +}, are considered, since these have also been used by previous workers in assigning the excited neutral state spectra. We also examine the vibrations of iodobenzene in the S{sub 0} and D{sub 0}{sup +} states and comment on the previous assignments of these. In summary, we have been able to assign the corresponding vibrations across the whole monohalobenzene series of molecules, in the S{sub 0}, S{sub 1}, and D{sub 0}{sup +} states, gaining insight into vibrational activity and vibrational couplings.

  6. Resonance-assisted decay of nondispersive wave packets.

    PubMed

    Wimberger, Sandro; Schlagheck, Peter; Eltschka, Christopher; Buchleitner, Andreas

    2006-07-28

    We present a quantitative semiclassical theory for the decay of nondispersive electronic wave packets in driven, ionizing Rydberg systems. Statistically robust quantities are extracted combining resonance-assisted tunneling with subsequent transport across chaotic phase space and a final ionization step.

  7. Influence of ionization on ultrafast gas-based nonlinear fiber optics.

    PubMed

    Chang, W; Nazarkin, A; Travers, J C; Nold, J; Hölzer, P; Joly, N Y; Russell, P St J

    2011-10-10

    We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

  8. Ionization of helium by intense XUV laser pulses: Numerical simulations on channel-resolved probabilities

    NASA Astrophysics Data System (ADS)

    Yu, Chuan; Madsen, Lars Bojer

    2016-04-01

    Ionization of a helium atom by intense extreme ultraviolet laser pulses is investigated in a frequency regime where the high-frequency stabilization condition is only fulfilled for the lowest single ionization channel. Multiphoton double ionization substantially contributes to the total ionization probability for superintense fields. As a result, no obvious stabilization against total ionization occurs. A detailed view of probabilities into different single ionization channels as a function of the field strength is presented. We find that the probabilities into some ionic channels peak at field strengths corresponding to one-photon resonances between field-dressed ionic states in the high-frequency Floquet theory. Thus we propose a sequential "ionization-excitation" mechanism in the dressed energy picture: first, one-photon absorption causes single ionization, leaving the ion in its dressed ground state; second, the ion is excited to a new state via one-photon absorption at the field strength where the resonance condition in the dressed ionic system is fulfilled. To reveal the sequential mechanism in the time domain, we also take a time-dependent view on the channel-resolved probabilities, observing the decrease of the ground-state ionic channel probability during the laser pulse when the field strength is such that a resonance condition exists between the dressed states in the ion.

  9. Shape resonances in molecular fields

    SciTech Connect

    Dehmer, Joseph L.

    1984-01-01

    A shape resonance is a quasibound state in which a particle is temporarily trapped by a potential barrier (i.e., the shape of the potential), through which it may eventually tunnel and escape. This simple mechanism plays a prominent role in a variety of excitation processes in molecules, ranging from vibrational excitation by slow electrons to ionization of deep core levels by x-rays. Moreover, their localized nature makes shape resonances a unifying link between otherwise dissimilar circumstances. One example is the close connection between shape resonances in electron-molecule scattering and in molecular photoionization. Another is the frequent persistence of free-molecule shape resonant behavior upon adsorption on a surface or condensation into a molecular solid. The main focus of this article is a discussion of the basic properties of shape resonances in molecular fields, illustrated by the more transparent examples studied over the last ten years. Other aspects to be discussed are vibrational effects of shape resonances, connections between shape resonances in different physical settings, and examples of shape resonant behavior in more complex cases, which form current challenges in this field.

  10. Sequence and structural characterization of great salt lake bacteriophage CW02, a member of the T7-like supergroup.

    PubMed

    Shen, Peter S; Domek, Matthew J; Sanz-García, Eduardo; Makaju, Aman; Taylor, Ryan M; Hoggan, Ryan; Culumber, Michele D; Oberg, Craig J; Breakwell, Donald P; Prince, John T; Belnap, David M

    2012-08-01

    Halophage CW02 infects a Salinivibrio costicola-like bacterium, SA50, isolated from the Great Salt Lake. Following isolation, cultivation, and purification, CW02 was characterized by DNA sequencing, mass spectrometry, and electron microscopy. A conserved module of structural genes places CW02 in the T7 supergroup, members of which are found in diverse aquatic environments, including marine and freshwater ecosystems. CW02 has morphological similarities to viruses of the Podoviridae family. The structure of CW02, solved by cryogenic electron microscopy and three-dimensional reconstruction, enabled the fitting of a portion of the bacteriophage HK97 capsid protein into CW02 capsid density, thereby providing additional evidence that capsid proteins of tailed double-stranded DNA phages have a conserved fold. The CW02 capsid consists of bacteriophage lambda gpD-like densities that likely contribute to particle stability. Turret-like densities were found on icosahedral vertices and may represent a unique adaptation similar to what has been seen in other extremophilic viruses that infect archaea, such as Sulfolobus turreted icosahedral virus and halophage SH1.

  11. Sequence and Structural Characterization of Great Salt Lake Bacteriophage CW02, a Member of the T7-Like Supergroup

    PubMed Central

    Shen, Peter S.; Sanz-García, Eduardo; Makaju, Aman; Taylor, Ryan M.; Hoggan, Ryan; Culumber, Michele D.; Oberg, Craig J.; Breakwell, Donald P.; Prince, John T.

    2012-01-01

    Halophage CW02 infects a Salinivibrio costicola-like bacterium, SA50, isolated from the Great Salt Lake. Following isolation, cultivation, and purification, CW02 was characterized by DNA sequencing, mass spectrometry, and electron microscopy. A conserved module of structural genes places CW02 in the T7 supergroup, members of which are found in diverse aquatic environments, including marine and freshwater ecosystems. CW02 has morphological similarities to viruses of the Podoviridae family. The structure of CW02, solved by cryogenic electron microscopy and three-dimensional reconstruction, enabled the fitting of a portion of the bacteriophage HK97 capsid protein into CW02 capsid density, thereby providing additional evidence that capsid proteins of tailed double-stranded DNA phages have a conserved fold. The CW02 capsid consists of bacteriophage lambda gpD-like densities that likely contribute to particle stability. Turret-like densities were found on icosahedral vertices and may represent a unique adaptation similar to what has been seen in other extremophilic viruses that infect archaea, such as Sulfolobus turreted icosahedral virus and halophage SH1. PMID:22593163

  12. Nonlinear optical response of multiply ionized noble-gas atoms

    NASA Astrophysics Data System (ADS)

    Tarazkar(1, 3), Maryam; Romanov(2, 3), Dmitri; Levis(1, 3), Robert

    2016-05-01

    Calculation of dynamic polarizabilities and hyperpolarizabilities of ionized species using ab initio methods presents computational and conceptual difficulties, as these ionized species often have open-shell electronic system. We use multi-configurational self-consistent field (MCSCF) method with extended basis sets for calculating dynamic polarizability and second-order hyperpolarizabilities of atomic noble gases and their multiply charged cations in non-resonant regime. The calculations were performed at wavelengths ranging from about 100 nm to the red of the first multi-photon resonance all the way toward the static regime. The results were benchmarked to those of CCSD calculations for ions of even-number charge. The second-order hyperpolarizability coefficients were found to decrease when the electrons are progressively removed from the system. At higher ionization states, these coefficients become less dispersive as a function of wavelength. The values and even the signs of the γ (2) coefficients were found to depend on the spin of the ionic quantum state. Thus, for Ne+3 and Ne+4, in low-spin states (2 Pu, and 1 Sg, respectively) the sign of γ (2) is positive, whereas in high-spin states (4 Su, and 3 Pg) the sign is negative. The calculated hyperpolarizabilities of multiply ionized atoms relate to experiments on very bright high-order harmonic generation in multiply ionized plasmas.

  13. Tevatron ionization profile monitoring

    SciTech Connect

    Jansson, A.; Bowie, K.; Fitzpatrick, T.; Kwarciany, R.; Lundberg, C.; Slimmer, D.; Valerio, L.; Zagel, J.; /Fermilab

    2006-06-01

    Ionization Profile monitors have been used in almost all machines at Fermilab. However, the Tevatron presents some particular challenges with its two counter-rotating, small beams, and stringent vacuum requirements. In order to obtain adequate beam size accuracy with the small signals available, custom made electronics from particle physics experiments was employed. This provides a fast (single bunch) and dead-timeless charge integration with a sensitivity in the femto-Coulomb range, bringing the system close to the single ionization electron detection threshold. The detector itself is based on a previous Main Injector prototype, albeit with many modifications and improvements. The first detector was installed at the end of 2005, and the second detector during the spring shutdown. The ultimate goal is to continuously monitor beam size oscillations at injection, as well as the beam size evolution during ramp and squeeze. Initial results are very encouraging.

  14. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  15. The multiphoton ionization of uranium hexafluoride

    SciTech Connect

    Armstrong, D.P. . UEO Enrichment Technical Operations Div.)

    1992-05-01

    Multiphoton ionization (MPI) time-of-flight mass spectroscopy and photoelectron spectroscopy studies of UF{sub 6} have been conducted using focused light from the Nd:YAG laser fundamental ({lambda}=1064 nm) and its harmonics ({lambda}=532, 355, or 266 nm), as well as other wavelengths provided by a tunable dye laser. The MPI mass spectra are dominated by the singly and multiply charged uranium ions rather than by the UF{sub x}{sup +} fragment ions even at the lowest laser power densities at which signal could be detected. The laser power dependence of U{sup n+} ions signals indicates that saturation can occur for many of the steps required for their ionization. In general, the doubly-charged uranium ion (U{sup 2+}) intensity is much greater than that of the singly-charged uranium ion (U{sup +}). For the case of the tunable dye laser experiments, the U{sup n+} (n = 1- 4) wavelength dependence is relatively unstructured and does not show observable resonance enhancement at known atomic uranium excitation wavelengths. The dominance of the U{sup 2+} ion and the absence or very small intensities of UF{sub x}{sup +} fragments, along with the unsaturated wavelength dependence, indicate that mechanisms may exist other than ionization of bare U atoms after the stepwise photodissociation of F atoms from the parent molecule.

  16. Hysteresis of ionization waves

    SciTech Connect

    Dinklage, A.; Bruhn, B.; Testrich, H.; Wilke, C.

    2008-06-15

    A quasi-logistic, nonlinear model for ionization wave modes is introduced. Modes are due to finite size of the discharge and current feedback. The model consists of competing coupled modes and it incorporates spatial wave amplitude saturation. The hysteresis of wave mode transitions under current variation is reproduced. Sidebands are predicted by the model and found in experimental data. The ad hoc model is equivalent to a general--so-called universal--approach from bifurcation theory.

  17. Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Marginean, Ioan; Tang, Keqi

    2014-06-13

    Electrospray Ionization (ESI) is a process whereby gas phase ions are created from molecules in solution. As a solution exits a narrow tube in the presence of a strong electric field, an aerosol of charged droplets are is formed that produces gas phase ions as they it desolvates. ESI-MS comprises the creation of ions by ESI and the determination of their mass to charge ratio (m/z) by MS.

  18. [HLA B13, B17, B37 and Cw6 in psoriasis vulgaris: relationship to age of onset (author's transl)].

    PubMed

    Mayr, W R; Gschnait, F; Brenner, W

    1979-03-01

    The frequency of HLA B13, B17, B37 and Cw6 was investigated in 77 patients with psoriasis vulgaris (57 patients with an onset of the disease between 10 and 20 years of age and 20 patients with an onset between 35 and 45 years). A highly significant increase in the frequency of the four HLA antigens tested was found. The highest relative risk was calculated for Cw6 (RR = 8.28). Furthermore, a significant positive association was observed between the presence of Cw6 and an early onset of psoriasis vulgaris.

  19. Dissociative ionization of biomolecules

    NASA Astrophysics Data System (ADS)

    Huo, Winifred

    2004-09-01

    Dissociative ionization (DI) by electron impact plays a role in many different applications, including low-temperature plasma processing, the study of space and astrophysical plasmas, and the study of biological damages by high-energy radiation. In the present study, our goal is to understand the health hazard to humans from exposure to radiation during an extended space flight. DI by secondary electrons can damage the DNA, either directly by causing a DNA lesion, or indirectly by producing radicals and cations that attack the DNA. The theoretical model employed makes use of the fact that electronic motion is much faster than nuclear motion, allowing DI to be treated as a two-step process. The first step is electron-impact ionization resulting in a dissociative state of the molecular ion with the same geometry as the neutral molecule. In the second step the ion relaxes from the initial geometry and undergoes unimolecular dissociation. Thus the DI cross section is given by the product of the ionization cross section and the dissociation probability. For the ionization process we use the improved binary-encounter dipole (iBED) model. For unimolecular dissociation, we use the multiconfigurational self-consistent field (MCSCF) method to determine the minimum energy pathways to possible product channels. This model has been applied to study the DI of H_2O, NH_3, and CH_4, and the results are in good agreement with experiment. The DI from the low-lying channels of benzene has also been studied and the dissociation products are compared with photoionization measurements. The DI of the DNA bases guanine and cytosine are then discussed. Of the four DNA bases, guanine has the largest ionization cross section and cytosine has the smallest. The guanine radical cation is considered to be one of the precursors to the primary, direct-type lesions formed in DNA when it is irradiated. Comparison of DI products of guanine and cytosine will be made to understand the differences in

  20. Differential high-resolution stimulated CW Raman spectroscopy of hydrogen in a hollow-core fiber.

    PubMed

    Westergaard, Philip G; Lassen, Mikael; Petersen, Jan C

    2015-06-15

    We demonstrate sensitive high-resolution stimulated Raman measurements of hydrogen using a hollow-core photonic crystal fiber (HC-PCF). The Raman transition is pumped by a narrow linewidth (< 50 kHz) 1064 nm continuous-wave (CW) fiber laser. The probe light is produced by a homebuilt CW optical parametric oscillator (OPO), tunable from around 800 nm to 1300 nm (linewidth ∼ 5 MHz). These narrow linewidth lasers allow for an excellent spectral resolution of approximately 10(-4) cm(-1). The setup employs a differential measurement technique for noise rejection in the probe beam, which also eliminates background signals from the fiber. With the high sensitivity obtained, Raman signals were observed with only a few mW of optical power in both the pump and probe beams. This demonstration allows for high resolution Raman identification of molecules and quantification of Raman signal strengths. PMID:26193604

  1. Upgrade and validation on plasma of the Tore Supra CW LHCD generator

    NASA Astrophysics Data System (ADS)

    Delpech, L.; Achard, J.; Armitano, A.; Berger-By, G.; Bertrand, E.; Bouquey, F.; Chaix, J. P.; Corbel, E.; Crest, I.; Ekedahl, A.; Faisse, F.; Fejoz, P.; Garibaldi, P.; Goletto, C.; Lebourg, P.; Leroux, F.; Lombard, G.; Magne, R.; Martinez, A.; Moreau, M.; Mollard, P.; Nicolas, L.; Pagano, M.; Poli, S.; Prou, M.; Raulin, D.; Samaille, F.; Soler, B.; Thouvenin, D.; Volpe, D.; Volpe, R.

    2011-12-01

    A one year-long major upgrade of the 3.7 GHz Lower Hybrid Current Drive (LHCD) generator for the Tore Supra (TS) tokamak has been performed. It consisted in installing a first series of eight Thales Electron Devices (TED) 700 kW CW klystrons, new CW components and auxiliaries, and in modifying the transmitter control and protection software. Modifications and calibration of the sensors and the RF subsystems were completed as well. Finally, the RF power available in the generator has been increased by 35% and the pulse duration could reach 1000 s. A complete validation and optimization of the klystrons have been performed in 2010 on matched load before the generator could enter into operation. The eight klystrons connected with the Full Active Multijunction (FAM) antenna delivered 3.5 MW/50s in December 2010. The upgrade of the generator and the steps to validate the modifications are described.

  2. HIGH AVERAGE CURRENT LOW EMITTANCE BEAM EMPLOYING CW NORMAL CONDUCTING GUN.

    SciTech Connect

    CHANG,X.; BEN-ZVI, I.; KEWISCH, J.; PAI, C.

    2007-06-25

    CW normal conducting guns usually do not achieve very high field gradient and waste much RF power at high field gradient compared to superconducting cavities. But they have less trapped modes and wakefields compared to the superconducting cavities due to their low Q. The external bucking coil can also be applied very close to the cathode to improve the beam quality. By using a low frequency gun with a recessed cathode and a carefully designed beam line we can get a high average current and a high quality beam with acceptable RF power loss on the cavity wall. This paper shows that the CW normal conducting gun can be a backup solution for those projects which need high peak and average current, low emittance electron beams such as the Relativistic Heavy Ion Collider (RHIC) e-cooling project and Energy Recovery Linac (Em) project.

  3. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene

    PubMed Central

    Okhrimchuk, Andrey G.; Obraztsov, Petr A.

    2015-01-01

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires–Tournois interferometer. PMID:26052678

  4. Multilayer optical data storage by fluorescence modulation using a CW laser

    NASA Astrophysics Data System (ADS)

    Singer, Kenneth D.; Christenson, Cory W.; Saini, Anuj; Ryan, Christopher J.; Mirletz, Heather; Shiyanovskaya, Irina; Yin, Kezhen; Baer, Eric

    2015-08-01

    Optical data storage has been widely used in certain consumer applications owing to its passive and robust nature, but has failed to keep with larger industry data storage needs due to the lack of capacity. Many alternatives have been proposed and developed, such as 3D data storage using two-photon absorption that require complex and dangerous laser systems to localize the bits. In this paper, we present a method for localizing bits using a CW 405nm laser diode, in a multilayered polymer film. Data is stored by photobleaching a fluorescent dye, and the response of the material is nonlinear, despite the CW laser and absorption in the visible region. This is achieved using sub-μs pulses from the laser initiating a photothermal effect. This writing method, along with the inexpensive roll-to-roll method for making the disc, will allow for terabyte-scale optical discs using conventional commercial optics and lasers.

  5. CW laser strategies for simultaneous, multi-parameter measurements in high-speed gas flows

    NASA Technical Reports Server (NTRS)

    Di Rosa, M. D.; Philippe, L. C.; Arroyo, M. P.; Hanson, R. K.

    1992-01-01

    Strategies utilizing continuous wave (CW) lasers are considered which are capable of simultaneously measuring the flow parameters of velocity, temperature, and pressure at sampling rates exceeding 3 kHz. Velocity is determined from the Doppler shift of the spectral profile, temperature is extracted from intensity ratios of multiple lines, and pressure is measured from either the collision of broadening or the magnitude of absorption. Distinctions between strategies concern the specifics of probe spacies (NO, OH, O2, and H2O) in terms of nominal probe wavelength, equipment, and detection scheme. CW lasers were applied to path-integrated absorption measurements of transient shock-tube flows and spatially resolved laser-induced fluorescence measurements of underexpanded jets.

  6. Development of a 9.3 micrometer CW LIDAR for the study of atmospheric aerosol

    NASA Technical Reports Server (NTRS)

    Whiteside, B. N.; Schotland, R. M.

    1993-01-01

    This report provides a brief summary of the basic requirements to obtain coherent or heterodyne mixing of the optical radiation backscattered by atmospheric aerosols with that from a fixed frequency source. The continuous wave (CW) mode of operation for a coherent lidar is reviewed along with the associated lidar transfer equation. A complete optical design of the three major subsystems of a CW, coherent lidar is given. Lens design software is implemented to model and optimize receiver performance. Techniques for the opto-mechanical assembly and some of the critical tolerances of the coherent lidar are provided along with preliminary tests of the subsystems. Included in these tests is a comparison of the experimental and the theoretical average power signal-to-noise ratio. The analog to digital software used to evaluate the power spectrum of the backscattered signal is presented in the Appendix of this report.

  7. Noise analysis for near field 3-D FM-CW radar imaging systems

    SciTech Connect

    Sheen, David M.

    2015-06-19

    Near field radar imaging systems are used for several applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit the performance in several ways including reduction in system sensitivity and reduction of image dynamic range. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  8. Design of a 1-MW CW 8.5 GHz transmitter for planetary RADAR

    NASA Technical Reports Server (NTRS)

    Hoppe, Daniel J.; Bhanji, Alaudin M.

    1990-01-01

    A proposed conceptual design for increasing the output power of an existing X-band planetary radar transmitter from 365 kW to 1 MW CW is discussed. The paper covers the basic transmitter system requirements as dictated by the specifications for the radar. The characteristics and expected performance of the high-power klystrons are considered and the transmitter power amplifier system is discussed. Also included in the discussion is the design of the exiter system. Two alternative feed systems for delivering the 1-MW CW signal to the antenna system are described. The expected performance of the beam supply, heat exchanger, and monitor and control devices is also presented. Finally, an assessment of the state-of-the-art technology to meet system requirements is given and possible areas of difficulty are summarized.

  9. CW Interference Effects on High Data Rate Transmission Through the ACTS Wideband Channel

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Ngo, Duc H.; Tran, Quang K.; Tran, Diepchi T.; Yu, John; Kachmar, Brian A.; Svoboda, James S.

    1996-01-01

    Satellite communications channels are susceptible to various sources of interference. Wideband channels have a proportionally greater probability of receiving interference than narrowband channels. NASA's Advanced Communications Technology Satellite (ACTS) includes a 900 MHz bandwidth hardlimiting transponder which has provided an opportunity for the study of interference effects of wideband channels. A series of interference tests using two independent ACTS ground terminals measured the effects of continuous-wave (CW) uplink interference on the bit-error rate of a 220 Mbps digitally modulated carrier. These results indicate the susceptibility of high data rate transmissions to CW interference and are compared to results obtained with a laboratory hardware-based system simulation and a computer simulation.

  10. Model Calculations of Continuous-Wave Laser Ionization of Krypton

    SciTech Connect

    Bret D. Cannon

    1999-07-27

    This report describes modeling of a scheme that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The models predict that combining this ionization scheme with mass spectrometric measurement of the resulting ions can be the basis for ultra-sensitive methods to measure {sup 85}Kr in the presence of a 10{sup 11} excess of the stable krypton isotopes. Two experimental setups are considered in this model: the first setup is for krypton as a static gas, the second is for krypton in an atomic beam. In the static gas experiment, for a total krypton press of 10{sup {minus}4} torr and 10 W of power in the cavity, the model predicts a total krypton ion current of 4.6 x 10{sup 8} s{sup {minus}1} and for a {sup 85}Kr/Kr of 10{sup {minus}11} a {sup 85}Kr ion current of 3.5 s{sup {minus}1} or about 10,000 per hour. The atomic beam setup allowed higher isotopic selectivity; the model predicts a {sup 85}Kr ion current of 18 s{sup {minus}1} or 65,000 per hour.

  11. Investigation of in-vivo skin autofluorescence lifetimes under long-term cw optical excitation

    SciTech Connect

    Lihachev, A; Ferulova, I; Vasiljeva, K; Spigulis, J

    2014-08-31

    The main results obtained during the last five years in the field of laser-excited in-vivo human skin photobleaching effects are presented. The main achievements and results obtained, as well as methods and experimental devices are briefly described. In addition, the impact of long-term 405-nm cw low-power laser excitation on the skin autofluorescence lifetime is experimentally investigated. (laser biophotonics)

  12. Coherent quasi-CW 153-nm light source at high repetition rate

    NASA Astrophysics Data System (ADS)

    Nomura, Yutaka; Ito, Yoshiaki; Ozawa, Akira; Wang, Xiaoyang; Chen, Chuangtian; Shin, Shik; Watanabe, Shuntaro; Kobayashi, Yohei

    2012-02-01

    We present a quasi-cw laser in vacuum ultraviolet region at megahertz repetition rate. The narrowband pulses generated from an ytterbium-fiber laser system at 33 MHz repetition rate at the central wavelength of 1074 nm is frequency-converted by successive stages of LBO crystals and KBBF crystals. The generated radiation at 153 nm has the shortest wavelength achieved through phase-matched frequency conversion processes in nonlinear optical crystals to our knowledge.

  13. Measurements of Partial Reflections at 3.18 Mhz Using the CW Radar Technique

    NASA Technical Reports Server (NTRS)

    Priese, J.; Singer, W.

    1984-01-01

    An equipment for measuring partial reflections using the FM-CW-radar principle at 3.18 MHz, installed at the Ionospheric Observatory Juliusruh of the CISTP (HHI), is described. The linear FM-chirp of 325 kHz bandwidth is Gaussian-weighted in amplitude and gives a height resolution of 1.5 km (chirp length is 0.6 sec). Preliminary results are presented for the first observation period in winter 1982/83.

  14. Simple analytical derivations of thermal lensing in longitudinally Q-CW pumped Yb:YAG.

    PubMed

    Bourdet, Gilbert L; Gouédard, Claude

    2010-08-01

    In this paper, we introduce analytical derivations for the thermal lensing of an end-pumped laser disk. These derivations are done for pump beam shapes from Gaussian to top hat, assuming that the thermal conductivity is either constant with the temperature or not. We give examples in two temperature regions, where the thermal conductivity exhibits T(-1) or T(-2) dependence. Numerical applications are given for a Q-CW pumped Yb:YAG disk laser. PMID:20676168

  15. Observation of spectral asymmetry in cw-pumped type II spontaneous parametric down-conversion

    SciTech Connect

    Zhao, Zhi; Meyer, Kent A; Whitten, William B; Shaw, Robert W; Bennink, Ryan S; Grice, Warren P

    2008-06-01

    We report on a spectral asymmetry in cw-pumped type II spontaneous parametric down-conversion. We observe that when the pump beam is focused, the spectra of ordinary and extraordinary down-converted photons broaden unequally. Theoretical analysis indicates that this asymmetry can be attributed to the difference in the angular dispersion (walk-off) of the two kinds of photons, coupled with the well-known correlation between wavelength and emission direction.

  16. Energy-time entanglement generation in optical fibers under CW pumping.

    PubMed

    Dong, Shuai; Zhou, Qiang; Zhang, Wei; He, Yuhao; Zhang, Weijun; You, Lixing; Huang, Yidong; Peng, Jiangde

    2014-01-13

    In this paper, the energy-time entangled photon-pairs at 1.5 μm are generated by the spontaneous four wave mixing (SFWM) in optical fibers under continuous wave (CW) pumping. The energy-time entanglement property is demonstrated experimentally through an experiment of Franson-type interference. Although the generation rates of the noise photons are one order of magnitude higher than that of the photon-pairs under CW pumping, the impact of noise photons can be highly suppressed in the measurement by a narrow time domain filter supported by superconducting nanowire single photon detectors with low timing jitters and time correlated single photon counting (TCSPC) module with high time resolution. The experiment results show that the SFWM in optical fibers under CW pumping provides a simple and practical way to generate energy-time entanglement at 1.5 μm, which has great potential for long-distance quantum information applications over optical fibers. PMID:24514996

  17. Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.

    DOEpatents

    Alfano, Robert R.; Wang, Wubao

    2003-05-06

    A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. A low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively.

  18. RF couplers for normal-conducting photoinjector of high-power CW FEL

    SciTech Connect

    Kurennoy, S.

    2004-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by 'dog-bone' irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  19. RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL

    NASA Astrophysics Data System (ADS)

    Kurennoy, Sergey; Schrage, Dale; Wood, Richard; Schultheiss, Tom; Rathke, John; Young, Lloyd

    2004-05-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be build for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  20. Continuous-wave deep ultraviolet sources for resonance Raman explosive sensing

    NASA Astrophysics Data System (ADS)

    Yellampalle, Balakishore; Martin, Robert; Sluch, Mikhail; McCormick, William; Ice, Robert; Lemoff, Brian

    2015-05-01

    A promising approach to stand-off detection of explosive traces is using resonance Raman spectroscopy with Deepultraviolet (DUV) light. The DUV region offers two main advantages: strong explosive signatures due to resonant and λ- 4 enhancement of Raman cross-section, and lack of fluorescence and solar background. For DUV Raman spectroscopy, continuous-wave (CW) or quasi-CW lasers are preferable to high peak powered pulsed lasers because Raman saturation phenomena and sample damage can be avoided. In this work we present a very compact DUV source that produces greater than 1 mw of CW optical power. The source has high optical-to-optical conversion efficiency, greater than 5 %, as it is based on second harmonic generation (SHG) of a blue/green laser source using a nonlinear crystal placed in an external resonant enhancement cavity. The laser system is extremely compact, lightweight, and can be battery powered. Using two such sources, one each at 236.5 nm and 257.5 nm, we are building a second generation explosive detection system called Dual-Excitation-Wavelength Resonance-Raman Detector (DEWRRED-II). The DEWRRED-II system also includes a compact dual-band high throughput DUV spectrometer, and a highly-sensitive detection algorithm. The DEWRRED technique exploits the DUV excitation wavelength dependence of Raman signal strength, arising from complex interplay of resonant enhancement, self-absorption and laser penetration depth. We show sensor measurements from explosives/precursor materials at different standoff distances.

  1. Type-I QW cascade diode lasers with 830 mW of CW power at 3 μm

    NASA Astrophysics Data System (ADS)

    Shterengas, L.; Liang, R.; Hosoda, T.; Kipshidze, G.; Belenky, G.; Bowman, S. S.; Tober, R. L.

    2015-03-01

    Cascade pumping schemes that utilize single-QW gain stages enhanced both the power conversion efficiency and the output power level of GaSb-based diode lasers that emit near and above 3 μm at room temperature. The cascade lasers discussed in this work had densely stacked type-I QWs gain stages characterized by high differential gain. The 3 μm emitting devices demonstrated CW threshold current densities near 100 A/cm2, a twofold improvement over the previous world record, that resulted in peak power conversion efficiencies increasing to 16% at 17°C. Comparable narrow ridge two-stage devices generated more than 100 mW of CW power with ~10% power conversion efficiencies. Three-stage multimode cascade lasers emitted 960 mW of CW output power near 3 μm and 120 mW CW near 3.3 μm.

  2. Progress in producing megawatt gyrotrons for ECR (electron cyclotron resonance) heating

    SciTech Connect

    Felch, K.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Tsirulnikov, M. )

    1990-10-01

    Varian is carrying out the development of high-power, CW gyrotrons at frequencies ranging from 100--500 GHz for use in electron cyclotron resonance (ECR) heating of magnetically-confined plasma. Initial test vehicles at 140 GHz have utilized TE{sub 15,2,1} interaction cavities, and have been designed to generate short-pulse (up to 20 ms) power levels of 1 MW and up to 400 kW CW. Recently, short-pulse power levels of 940 kW at 35% efficiency have been obtained and average powers of 200 kW have been achieved at peak powers of 400 kW. Long-pulse testing is currently underway. Initial test have resulted in output levels of 400 kW for pulse durations of 380 ms. Design work on 110 GHz, 500 kW CW gyrotron oscillators has recently been completed and a prototype tube has been assembled and is currently being tested. The design of a 110 GHz, 1 MW CW gyrotron, using a novel output coupling approach, is nearly complete. Fabrication of the first 1 MW CW experimental tube is in progress.

  3. Optical resonator

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    The invention discloses a semi-ring Fabry-Perot (SRFP) optical resonator structure comprising a medium including an edge forming a reflective facet and a waveguide within the medium, the waveguide having opposing ends formed by the reflective facet. The performance of the SRFP resonator can be further enhanced by including a Mach-Zehnder interferometer in the waveguide on one side of the gain medium. The optical resonator can be employed in a variety of optical devices. Laser structures using at least one SRFP resonator are disclosed where the resonators are disposed on opposite sides of a gain medium. Other laser structures employing one or more resonators on one side of a gain region are also disclosed.

  4. More than 100 channel supercontinuum CW optical source with precise 25GHz spacing for 10Gbit/s DWDM systems

    NASA Astrophysics Data System (ADS)

    Wang, Jianping; Nan, Yinbo; Zhou, Xianwei

    2006-01-01

    We experimentally demonstrate the generation of supercontinuum (SC) with a 12.5GHz DFB/EAM ultrashort optical pulse broadened in the high nonlinear fiber (HNLF). Through longitudinal mode-carving of the SC spectrum, a novel multiwavelength continuous wave (CW) optical source with precise 25GHz channel spacing is realized. The bit error rate (BER) curve and eye diagram show that the multiwavelength CW optical source is promising for dense wavelength division multiplexing (DWDM) systems.

  5. Observations of tornadoes and wall clouds with a portable FM-CW Doppler radar: 1989--1990 results

    SciTech Connect

    Bluestein, H.B. . School of Meteorology); Unruh, W.P. )

    1990-01-01

    The purpose of this paper is to report on our progress using a portable, 1 W,FM (frequency modulated)-CW (continuous wave) Doppler radar developed at the Los Alamos National Laboratory (LANL), to make measurements of the wind field in tornadoes and wall clouds along with simultaneous visual documentation. Results using a CW version of the radar in 1987--1988 are given in Bluestein and Unruh (1989). 18 refs., 2 figs., 1 tab.

  6. Antiviral Activity of a Novel Compound CW-33 against Japanese Encephalitis Virus through Inhibiting Intracellular Calcium Overload.

    PubMed

    Huang, Su-Hua; Lien, Jin-Cherng; Chen, Chao-Jung; Liu, Yu-Ching; Wang, Ching-Ying; Ping, Chia-Fong; Lin, Yu-Fong; Huang, An-Cheng; Lin, Cheng-Wen

    2016-01-01

    Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, has five genotypes (I, II, III, IV, and V). JEV genotype I circulates widely in some Asian countries. However, current JEV vaccines based on genotype III strains show low neutralizing capacities against genotype I variants. In addition, JE has no specific treatment, except a few supportive treatments. Compound CW-33, an intermediate synthesized derivative of furoquinolines, was investigated for its antiviral activities against JEV in this study. CW-33 exhibited the less cytotoxicity to Syrian baby hamster kidney (BHK-21) and human medulloblastoma (TE761) cells. CW-33 dose-dependently reduced the cytopathic effect and apoptosis of JEV-infected cells. Supernatant virus yield assay pinpointed CW-33 as having potential anti-JEV activity with IC50 values ranging from 12.7 to 38.5 μM. Time-of-addition assay with CW-33 indicated that simultaneous and post-treatment had no plaque reduction activity, but continuous and simultaneous treatments proved to have highly effective antiviral activity, with IC50 values of 32.7 and 48.5 μM, respectively. CW-33 significantly moderated JEV-triggered Ca(2+) overload, which correlated with the recovery of mitochondria membrane potential as well as the activation of Akt/mTOR and Jak/STAT1 signals in treated infected cells. Phosphopeptide profiling by LC-MS/MS revealed that CW-33 upregulated proteins from the enzyme modulator category, such as protein phosphatase inhibitor 2 (I-2), Rho GTPase-activating protein 35, ARF GTPase-activating protein GIT2, and putative 3-phosphoinositide-dependent protein kinase 2. These enzyme modulators identified were associated with the activation of Akt/mTOR and Jak/STAT1 signals. Meanwhile, I-2 treatment substantially inhibited the apoptosis of JEV-infected cells. The results demonstrated that CW-33 exhibited a significant potential in the development of anti-JEV agents. PMID:27563890

  7. Antiviral Activity of a Novel Compound CW-33 against Japanese Encephalitis Virus through Inhibiting Intracellular Calcium Overload

    PubMed Central

    Huang, Su-Hua; Lien, Jin-Cherng; Chen, Chao-Jung; Liu, Yu-Ching; Wang, Ching-Ying; Ping, Chia-Fong; Lin, Yu-Fong; Huang, An-Cheng; Lin, Cheng-Wen

    2016-01-01

    Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, has five genotypes (I, II, III, IV, and V). JEV genotype I circulates widely in some Asian countries. However, current JEV vaccines based on genotype III strains show low neutralizing capacities against genotype I variants. In addition, JE has no specific treatment, except a few supportive treatments. Compound CW-33, an intermediate synthesized derivative of furoquinolines, was investigated for its antiviral activities against JEV in this study. CW-33 exhibited the less cytotoxicity to Syrian baby hamster kidney (BHK-21) and human medulloblastoma (TE761) cells. CW-33 dose-dependently reduced the cytopathic effect and apoptosis of JEV-infected cells. Supernatant virus yield assay pinpointed CW-33 as having potential anti-JEV activity with IC50 values ranging from 12.7 to 38.5 μM. Time-of-addition assay with CW-33 indicated that simultaneous and post-treatment had no plaque reduction activity, but continuous and simultaneous treatments proved to have highly effective antiviral activity, with IC50 values of 32.7 and 48.5 μM, respectively. CW-33 significantly moderated JEV-triggered Ca2+ overload, which correlated with the recovery of mitochondria membrane potential as well as the activation of Akt/mTOR and Jak/STAT1 signals in treated infected cells. Phosphopeptide profiling by LC-MS/MS revealed that CW-33 upregulated proteins from the enzyme modulator category, such as protein phosphatase inhibitor 2 (I-2), Rho GTPase-activating protein 35, ARF GTPase-activating protein GIT2, and putative 3-phosphoinositide-dependent protein kinase 2. These enzyme modulators identified were associated with the activation of Akt/mTOR and Jak/STAT1 signals. Meanwhile, I-2 treatment substantially inhibited the apoptosis of JEV-infected cells. The results demonstrated that CW-33 exhibited a significant potential in the development of anti-JEV agents. PMID:27563890

  8. Engineered Ionizable Side Chains.

    PubMed

    Cymes, Gisela D; Grosman, Claudio

    2015-01-01

    One of the great challenges of mechanistic ion-channel biology is to obtain structural information from well-defined functional states. In the case of neurotransmitter-gated ion channels, the open-channel conformation is particularly elusive owing to its transient nature and brief mean lifetime. In this Chapter, we show how the analysis of single-channel currents recorded from mutants engineered to contain single ionizable side chains in the transmembrane region can provide specific information about the open-channel conformation without any interference from the closed or desensitized conformations. The method takes advantage of the fact that the alternate binding and unbinding of protons to and from an ionizable side chain causes the charge of the protein to fluctuate by 1 unit. We show that, in mutant muscle acetylcholine nicotinic receptors (AChRs), this fluctuating charge affects the rate of ion conduction in such a way that individual proton-transfer events can be identified in a most straightforward manner. From the extent to which the single-channel current amplitude is reduced every time a proton binds, we can learn about the proximity of the engineered side chain to the lumen of the pore. And from the kinetics of proton binding and unbinding, we can calculate the side-chain's affinity for protons (pK a), and hence, we can learn about the electrostatic properties of the microenvironment around the introduced ionizable group. The application of this method to systematically mutated AChRs allowed us to identify unambiguously the stripes of the M1, M2 and M3 transmembrane α-helices that face the pore's lumen in the open-channel conformation in the context of a native membrane. PMID:26381938

  9. Features of radiation beam formation in resonators with perforated mirrors

    SciTech Connect

    Boreysho, A S; Leonov, A F; Strakhov, S Yu; Trilis, A V

    2003-02-28

    The possibility of using perforated output mirrors in stable resonators of cw CO{sub 2} lasers is discussed. The main factors responsible for the intracavity losses, including those connected with the diffraction of beams at the edges of holes in the mirrors are considered. The results of the experimental investigation of a 100-kW combustion product gas-dynamic CO{sub 2} laser with stable and unstable resonators and output mirrors of various types are compared with the results of numerical simulation. The theoretical and experimental studies performed over a wide range of parameters explain some peculiarities of the beam formation process in resonators with perforated mirrors. Practical recommendations are offered for choosing the parameters of such mirrors. (resonators)

  10. Design and characterization of a novel toroidal split-ring resonator

    NASA Astrophysics Data System (ADS)

    Bobowski, J. S.; Nakahara, Hiroko

    2016-02-01

    The design and characterization of a novel toroidal split-ring resonator (SRR) are described in detail. In conventional cylindrical SRRs, there is a large magnetic flux within the bore of the resonator. However, there also exists a non-negligible magnetic flux in the free space surrounding the resonator. The energy losses associated with this radiated power diminish the resonator's quality factor. In the toroidal SRR, on the other hand, the magnetic field lines are strongly confined within the bore of the resonator resulting in high intrinsic quality factors and stable resonance frequencies without requiring additional electromagnetic shielding. This paper describes the design and construction of a toroidal SRR as well as an experimental investigation of its cw response in the frequency-domain and its time-domain response to a rf pulse. Additionally, the dependence of the toroidal SRR's resonant frequency and quality factor on the strength of inductive coupling to external circuits is investigated both theoretically and experimentally.

  11. Nonsequential double ionization of molecules

    SciTech Connect

    Prauzner-Bechcicki, Jakub S.; Sacha, Krzysztof; Zakrzewski, Jakub; Eckhardt, Bruno

    2005-03-01

    Double ionization of diatomic molecules by short linearly polarized laser pulses is analyzed. We consider the final stage of the ionization process, that is the decay of a highly excited two electron molecule, which is formed after rescattering. The saddles of the effective adiabatic potential energy close to which simultaneous escape of electrons takes place are identified. Numerical simulations of the ionization of molecules show that the process can be dominated by either sequential or nonsequential events. In order to increase the ratio of nonsequential to sequential ionizations very short laser pulses should be applied.

  12. Stochastic resonance

    NASA Astrophysics Data System (ADS)

    Gammaitoni, Luca; Hänggi, Peter; Jung, Peter; Marchesoni, Fabio

    1998-01-01

    Over the last two decades, stochastic resonance has continuously attracted considerable attention. The term is given to a phenomenon that is manifest in nonlinear systems whereby generally feeble input information (such as a weak signal) can be be amplified and optimized by the assistance of noise. The effect requires three basic ingredients: (i) an energetic activation barrier or, more generally, a form of threshold; (ii) a weak coherent input (such as a periodic signal); (iii) a source of noise that is inherent in the system, or that adds to the coherent input. Given these features, the response of the system undergoes resonance-like behavior as a function of the noise level; hence the name stochastic resonance. The underlying mechanism is fairly simple and robust. As a consequence, stochastic resonance has been observed in a large variety of systems, including bistable ring lasers, semiconductor devices, chemical reactions, and mechanoreceptor cells in the tail fan of a crayfish. In this paper, the authors report, interpret, and extend much of the current understanding of the theory and physics of stochastic resonance. They introduce the readers to the basic features of stochastic resonance and its recent history. Definitions of the characteristic quantities that are important to quantify stochastic resonance, together with the most important tools necessary to actually compute those quantities, are presented. The essence of classical stochastic resonance theory is presented, and important applications of stochastic resonance in nonlinear optics, solid state devices, and neurophysiology are described and put into context with stochastic resonance theory. More elaborate and recent developments of stochastic resonance theory are discussed, ranging from fundamental quantum properties-being important at low temperatures-over spatiotemporal aspects in spatially distributed systems, to realizations in chaotic maps. In conclusion the authors summarize the achievements

  13. Energy-transfer studies and efficient cw laser operation of a cw Er,Yb:YCOB laser at 1.55 μm

    NASA Astrophysics Data System (ADS)

    Burns, Phillip A.; Dawes, Judith M.; Dekker, Peter; Piper, James A.; Jiang, Haidong; Jiang, Huiajing; Wang, Jiyang

    2003-06-01

    All-solid-state laser devices operating in the 1.5 - 1.6 μm wavelength range have many practical applications. The most notable of these is their use in optical telecommunications, but the current research drive is to increase the output power from high beam quality, solid-state devices for eye-safe applications such as laser range finding and target acquisition, remote sensing of trace elements in air, light detecting and ranging, medicine, metrology and atmospheric phenomena such as measurements of wind shear. Yb3+ ions are co-doped into the host material to improve the pumping efficiency by taking advantage of commercial InGaAs diode lasers emitting at 980 nm. The absorbed pump is then non-radiative transferred to the Er3+ ions, and rapidly decaying to the 4I13/2 upper-laser level. Laser operation in Er,Yb co-doped systems has been dominated by glass hosts (in particular, phosphate) with attempts in crystalline materials yielding disappointing results despite their superior mechanical and thermal properties. In this paper we will present efficient diode-pumped laser operation of the crystalline host material Er,Yb:YCOB at 1.55 μm. By studying the energy transfer mechanisms of this material, we have identified the optimum dopant concentrations and 250 mW of continuous wave (cw) output in TEM00 transverse mode has been obtained with a 2mm crystal in an hemispherical cavity. Also, >150 mW cw has been obtained in a flat-flat cavity arrangement. The output coupling in each case was 1%. The slope efficiency of the laser was 21.9%.

  14. Exploring Structure, Dynamics, and Topology of Nitroxide Spin-Labeled Proteins Using Continuous-Wave Electron Paramagnetic Resonance Spectroscopy.

    PubMed

    Altenbach, Christian; López, Carlos J; Hideg, Kálmán; Hubbell, Wayne L

    2015-01-01

    Structural and dynamical characterization of proteins is of central importance in understanding the mechanisms underlying their biological functions. Site-directed spin labeling (SDSL) combined with continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy has shown the capability of providing this information with site-specific resolution under physiological conditions for proteins of any degree of complexity, including those associated with membranes. This chapter introduces methods commonly employed for SDSL and describes selected CW EPR-based methods that can be applied to (1) map secondary and tertiary protein structure, (2) determine membrane protein topology, (3) measure protein backbone flexibility, and (4) reveal the existence of conformational exchange at equilibrium. PMID:26477248

  15. Multiphoton ionization of Uracil

    NASA Astrophysics Data System (ADS)

    Prieto, Eladio; Martinez, Denhi; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2016-05-01

    Multiphoton ionization and dissociation of Uracil using a Reflectron time of flight spectrometer was performed along with radiation from the second harmonic of a Nd:YAG laser. Uracil is one of the four nitrogen bases that belong to RNA. The last years special interest has been concentrated on the study of the effects under UV radiation in nucleic acids1 and also in the role that this molecule could have played in the origin and development of life on our planet.2 The MPI mass spectra show that the presence and intensity of the resulting ions strongly depend on the density power. The identification of the ions in the mass spectra is presented. The results are compared with those obtained in other laboratories under different experimental conditions and some of them show partial agreement.3 The present work was supported by CONACYT-Mexico Grant 165410 and DGAPA UNAM Grant IN101215 and IN102613.

  16. Ionized cluster beam deposition

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, A. R.

    1983-11-01

    Ionized Cluster Beam (ICB) deposition, a new technique originated by Takagi of Kyoto University in Japan, offers a number of unique capabilities for thin film metallization as well as for deposition of active semiconductor materials. ICB allows average energy per deposited atom to be controlled and involves impact kinetics which result in high diffusion energies of atoms on the growth surface. To a greater degree than in other techniques, ICB involves quantitative process parameters which can be utilized to strongly control the characteristics of films being deposited. In the ICB deposition process, material to be deposited is vaporized into a vacuum chamber from a confinement crucible at high temperature. Crucible nozzle configuration and operating temperature are such that emerging vapor undergoes supercondensation following adiabatic expansion through the nozzle.

  17. Ionizing radiation detector

    DOEpatents

    Thacker, Louis H.

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  18. Ionized cluster beam deposition

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, A. R.

    1983-01-01

    Ionized Cluster Beam (ICB) deposition, a new technique originated by Takagi of Kyoto University in Japan, offers a number of unique capabilities for thin film metallization as well as for deposition of active semiconductor materials. ICB allows average energy per deposited atom to be controlled and involves impact kinetics which result in high diffusion energies of atoms on the growth surface. To a greater degree than in other techniques, ICB involves quantitative process parameters which can be utilized to strongly control the characteristics of films being deposited. In the ICB deposition process, material to be deposited is vaporized into a vacuum chamber from a confinement crucible at high temperature. Crucible nozzle configuration and operating temperature are such that emerging vapor undergoes supercondensation following adiabatic expansion through the nozzle.

  19. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  20. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.